K.
Congratulations on your pregnancy! We have 2 kids 25 months apart. Moved my older son into a "big boy bed" at 20 months and this was no problem at all. Kept the baby in our bedroom in our bed/co-sleeper until she was 7 months (this is much longer than we had kept our first in our room, but it was working for us all). At around 7-8 months she got so rolly that we moved her into her own crib, but again kept it in our bedroom. Around 12-13 months, once she started sleeping through the night with some regularity, we moved her into the shared kids room. We let him "camp" on our floor for a few nights so that she could have a little time to fuss and get used to the new location without disturbing him. Now they've been in the same room for about 3 months and it's generally fine. She still wakes up around 50% of the time at night - he usually sleeps right through it, though occasionally will yell at her to stop. Depends on how long we let her yell before coming in. My advice would be to not worry so much about the space - the shared room thing is fine, and I suspect it will continue to be fine until he gets to be around 8 or 9 years old and decides he'd rather have his own room.