K.T.
We went thru the same thing here a couple years ago when our 2nd child was coming. The only thing I would suggest is before he starts sleeping in there full time, make sure he is able to spend lots of time in there. Let him play in there, with and without you and let him get use to it, maybe even take naps in there for a week or so first before you put him in there for sleeping at night. But once he transitions to sleeping in there at night, he might not like it at first, but just stick with it, it might be like having a newborn all over again, just reassure him his new room is a safe place just like his old room. Congrats on the new baby on the way too!!