". I just feel like we are trying so hard to make things okay for a kid that we see 6 weeks per year. I am worried about how SS will feel, how BM will take it and/or what drama she will try to cause, etc. I just feel like I'm worried about making this okay for everyone bu  t myself. "

Oh hon, step life makes everything complicated.  BUT, IMO you are WAY over-thinking this and approaching it in a WAY over the top coddling way for the SS -that as you said, you only see 6 weeks a year.

I would tell him when he visits in Dec.  Kids don't need as long to adjust to the idea as you think, they aren't adults.  He will have 3 months (pregnancy lasts 10 months really lol) - before baby is born. That is plenty of time.  As for the room, absolutely do NOT move the baby things out for the SS for the probably one time he will have to share since you will be buying a house.  That sends a horrible message to both kids iMO and just gives in to the special snowflake treatment.  Thousands of siblings share a room with their brother,  you can take baby into the room if you want, but you do not undress the room to make it look like your SS still has his room that sits empty all year and the baby has no PLACE in your home.  It gives the wrong message to SS IMO.  As older siblings do when a little one comes along, they learn to share a room.  

Don't worry at all about what BM will say/do, this will ruin your pregnancy and do not over-think with the kid.

Tell him in Dec.  Skip the Feb visit, have him in summer and give him a heads up he is sharing a room w/his brother now before he arrives.  They don't need to process or go to therapy to adjust to normal life situations.  I think the drama w/the bm is putting you guys on such edge you aren't thinking clearly.

As you said, if you drop rope, so be it, if you don't-do NOT bend yourselves backwards or your own child to sacrifice for the special/sensitive SS and his drama.  Go on with life as normal, with no effs given and NO special treatment for the kid.

Also "DH offered to relocate all of the baby's stuff prior to each visitation and set up SS' room back to its original condition, and then put it all back when he leaves, but our apartment is too small to find places to put everything just to make his room his."

I bet he did offer, but again, this is an absolute 100pct HARD NO and I would say over my dead body.  This is absolutely beyond absurd to do.  You are playing the twisting into a pretzel as BM and this kid apparently have you conditioned to do.  He's too scared to be a parent to BOTH kids but not protecting your child place and is teaching his older son that he matters more then anyone else.  I cannot emphasize enough how much of a horrible idea this is.  One of the worst 'ideas' I've seen when it comes to the bedroom debates.  I'm so sorry this situation has you guys like this, but the trauma is apparent because this would not ever normally be an even close to logical idea.

Yest, she has you both conditioned through trauma.  Even more reason your DH needs to treat him normal and not worship at the altar of SS.  I have a feeling once BM finds out about your pregnancy she will amp up the crazy 100pct and fill SS with thoughts about he's a  nobody to dad now and that only your kid matters.  I could be wrong, but if you dont' drop rope now with these accusations, it will likely come shortly after your child is born.  Your DH sadly will have to decide if he wants years or more torment and a SS who is constantly conflicted and in loyalty binds, or drop rope, stop the war, and focus on his family with you.  It's not looking good.  We have so many that fought legal battles for years, finances destroyed, which affects their own family and together kids, emotions destroyed, physical and mental health destroyed -leaving less of you to give to your kids because of all the hell.  If you have a hell bent BM in PAS'ing the kid from the start, IMO these men are better off letting go earlier then later to give the new family a chance of happiness and thriving and not just simply surviving in a myriad of hellish battles for years.  

Do not tell SS one second before you're comfortable doing so. That means he isn't told during his next visitation. December is soon enough. That will limit the SS/BM drama, which you know is coming, to just a couple months of your pregnancy.

As for rooms, SS and baby can share for the measly 6 weeks (if that going forward) he's with you. Don't move furniture and baby stuff  and don't move the baby unless you're concerned about safety. Kids share, period.

Sadly, my guess is that between the BM harassment, SS's lies and entitlement, the false abuse allegations and the judge who thinks your DH should pay his CS and go away, SS is going to be less and less present and relevant in your lives, so I wouldn't waste too much angst and mental energy on how/when to tell him. I doubt it'll matter in the long run.

Definitely agree with waiting until December.  Babies take forever to get here.  Three months is more than enough time to get accustom to the idea (especially if there's no chance someone else will blow it and tell him.  Like grandparents, or facebook friends etc.).

As for moving the stuff, I actually agree with DH.  If there's a real chance that you're going to be buying a house with a spare room that SS will usually stay in, so he will never be sharing with the baby, I'd move it too.  For the sake of ONE visit, why give him any reason to feel like he's being replaced.  Now, if he's going to share going forward - then start as you intend to continue and share the room.

The only thing I really disagree with is skipping the February visit.  You only have him 6 weeks of the year.  It's not fair to him or to your DH to say that the newborn replaces him.  I understand the urge to nest (trust me!!!), but the reality is that he exists.  You need to make room in your family for him.  If the baby is very new, DH needs to figure out who will come to watch over him while you're settling in with the baby.  Perhaps a grandmother could stay at the same time?  If the baby isn't here yet SS may have the excitement of being there when his little sibling is born!  But to cancel a February visit and make him wait all the way to summer to see his father again seems cruel.  If you can't reschedule it, I wouldn't cancel it.  Just make sure that DH has figured out a way to ensure that you're not expected to care for a brand new baby and SS at the same time.  Who knows, you might even deliver late (many first pregnancies do).

I'm wondering why you would want to re-inforce SS's behavior though?  I think it would be a REAL teaching moment that hey, you may have to share the room with baby until we buy a new house.  I would maybe even announce it when they do the pregnancy.  As in, make it one of inclusion, not that he's being displaced.  Brothers room up all the time.  Maybe discuss the pregnancy at start of the visit, about half way through tell him how they will be able to share the room for a few visits but you guys are looking for a house.  I wouldn't promise his own room because an unused room almost an entire year is unrealistic.  It's possible by then they will use it as an office and his room.  ANY kid that sees their parent 6 weeks a year should not expect a full room dedicated to them IMO.  Then they might have more kids, etc.  Best the kid learns at dads he will have to share.  Make it an exciting thing that he's having a brother and all the things they will be able to do one day.

As to the Feb visit, I also disagree, this kid brings a LOT of drama with him because of BM, the OP does not need to deal with that with a brand new baby immediately after having given birth.  Maybe if the kid wouldn't feed BS to his mom about how abusive they are it could be different- but I would not put that on ANY new mom.  If it were a normal situation w/out PAS then sure, dad can stay home WITH mom and the kid to take care of his kid.  Maybe that could be an option ONLY if dad will take the time off to be there too -most companies have some kind of paternity leave anyways.  Most kids also don't care to meet their siblings as soon as they are born, that's something we adults put on them.  Meeting him when he's a few months old will be a lot more fun- they smile, they coo, the do cute baby things- when newborns they are just a big blob that sleeps and nurses all the time.  Which is another thing- let the OP be comfy nursing in her home w/out further accusations of abuse from BM because SS was exposed to her nursing. And NO she doesn't lock herself in the room to appease the BS>  

I think no matter what you do BM will spin it in a negative direction. If you tell him now she will be planting seeds in his head the remainder of your pregnancy. She will most likely do whatever she can to torture you and your DH the whole time and try to stress you out (which you do not need). If you tell him at 7 months she will be shocked and go off the deep end for not telling him sooner.

Honestly, just worry about taking care of yourself, preparing for the baby, and your DH. Do what you want.. Your BM sounds toxic and will probably do anything she can to ruin this joyous time for you. As far as moving the stuff I personally wouldn't. I would say "hey we don't have a ton of space and until we get a new house we have to make room". We all have to make sacrifices as a family and leave it at that.

We only had my SD 2-4 days a month and her room sat empty and unused. It was a waste. Just speaking from my opinion/ experience, the kid sounds like a nightmare as well as the BM. You only have him 6 weeks a year. I'm sure his mom will brainwash him against you all especially when she finds out you are pregnant. Maybe you won't have to worry about it long term, if your lucky.

There is no win here. BM will use this as another way to alienate your DH from SS.

I agree with waiting until December, and I really wouldn't put too much thought into the rest of it. Yes, the kids might be sharing space for a while and that is ok. Likely during those 2 week visits the baby will be with you in your room. For 6 weeks a year he doesn't need a bedroom shrine dedicated to him. In the coming visits things will change, but that is life. 

Wait until December. DON"T tell him before that and if you announce it on FB make sure your settings are super locked down so the BM doesn't get wind of it either. Here are my thoughts on why. Pregnancy is hard enough on your body and mental state without the added dread of dealing with an abusive POS BM and her snowflake kid. Your emotional state plays a HUGE role on how your baby feels, everything you do and feel is passed onto your child. So protect him/her in every way possible. As far as baby and SS sharing a room goes. The first 6 months of the babies life, I personally would leave the crib in your bedroom. Move him into the other bedroom once he is sleeping thru the night and can let SS have a good nights sleep as well. They should share a bedroom, it doesn't make sense to move stuff in and out of a room to make the SS feel good about himself. They are siblings, siblings share bedrooms, that's just the way it is. I would also install a camera in that room, just to be safe. Try and enjoy your pregnancy. Your SS is around 6 weeks out of 52. Grin and bear it. It'll be fine.

Ohh Ohh Ohhh... I know the answer to this....my SD's mother mailed a valentines card to SD (we do long distance too) with an ultra sound of her baby ....no other explanation....no phone call....then left it to us to tell SD what it was (she didn't know what it was) and what it meant....As your due date is in february maybe don't tell him what is happening until next february then mail a valentines card with a photo of you, your DH and the new babs....?

Just kidding...that was an example of how NOT to announce a new baby to a sibling...though it didn't seem to affect SD and we are reasonable people so had a reasonable reaction for SD rather than trying to PAS her or tell her she is being replaced or anything. 

I agree with the  others, wait until December to tell him. I would also not tell him about the baby and him sharing a room. The baby should sleep in your room for at least 6 months anyway and you think you might get a new place by next summer so SS should be able to keep a room to himself. You don't need to set up a nursery until the baby moves out of your room. My 5 month old is still in with us and we have yet to sort out his bedroom and build his crib etc.