New room

Hi! So we have a new baby sister arriving in two months and are moving big brother into a new room so that the baby can get the nursery. He is going to be four in a month and wanted to decorate with the stuff he likes so we figured why decorate two rooms... he can have the new room with his decorations and the baby can have the existing room.

So my question is... how long did it take your toddler to transition to a new room? He will have the same bed, bookcase, etc. plus the new decorations he picked out on the walls. At 7 months pregnant I'm just curious what kind of sleep to expect! Thanks !