I'm pregnant with number 4. My oldest is 4, the second oldest is going to be 3, and the 3rd is 18 months. Now. We live in a 3 bedroom house, and all 3 of my boys (1,3,and new baby) will share a room. We currently have 1 crib, 1 toddler bed, and a broken crib/toddler bed combo (she's been sleeping on her mattress on the floor til we got something figured out.) our toddler bed converts to a twin bed. 

Which leads me to this. Hubs and I were thinking about getting bunk beds for the boys' room, and then letting the girl have the toddler bed, and the new baby the crib.  The new baby probably won't be in its crib until the 3rd child is 2 (may to August, I figure he will probably be in our room in the sleeper). So do we purchase the bunk beds, and leave the bottom bed empty until we transition 3 to big boy bed and 4 to his crib? Or do we try to transition 3 to the big boy bed as soon as we set it up? The bunk beds are the ones with stairs, so I'm not too worried about the 4 year old not being able to do the bunk beds, I'm more worried about the 18 month old transitioning from crib to bed.