We had the exact same situation when my son was approaching two years old and his sister was on the way. He was in the "nursery" in his crib and we wanted to switch his room and change him to the toddler bed so the new arrival to have the nursery/crib. Here's what we did: before the baby came, we moved him to the new room in his crib. We put the toddler bed in the new room, but didn't have him sleep in it. He just used to it being in there, was able to play in it, etc. Then after a couple of weeks, we started putting him down to sleep in the toddler bed. The crib was still in the room. After the baby was born, we had her sleep in the nursery in a bassinet for a couple weeks. Then we dismantled the crib and moved it out of my sons room and into the nursery. He never seemed disturbed at this transition, after the baby arrived I think it made sense to him that the crib should be in her room. So anyway, we did it in a few steps. A little tip, though: If you are calm and matter of fact through these transitions, chances are better that your son will be too. He will be able to pick up on your moods and stress levels and he will react accordingly. Good luck!