New baby and bedroom arrangements.

We haven’t told anyone that we’re expecting yet and my husband is at work so I figure I’d ask on here 🤓 We have a 4 bedroom house. All bedrooms are on the top floor. Master, big room, medium room and smaller room. Currently, the bigger room is my step daughter’s, the med is my step son’s and the smallest is our 19 month old’s and it is closest to our master. My step kids are with us every other weekend. We just found out we are expecting our 2nd. We are going to move my step son into the largest room with my step daughter. There is plenty of room for both beds, both dressers and a desk. They are very close and share a room at their mom’s so that is fine. I am just not sure what to do for our toddler and the new baby. Option 1 is to move our toddler into the medium room, set up his “big boy room” and then keep the smaller room for the nursery. Option 2 is to just make the med room the new baby’s nursery and keep my toddler in his current room. Our toddler is still in a crib, and I’d like to keep him in there for as long as he will stay in it. He’s a pretty awful sleeper and has been since day one but he’s very comfortable in his room and I’m nervous to “uproot” him. I know we have about 6 months to figure this out but this is stressing me out already 🙄 What would you do?