Unless it has changed, which it may, when my son sent his money in he had to indicate which check in date he preferred.
Also, there are a couple different college housing sights. My son had 5 people in his 6 bed apartment. Disney Housing did allow them a week later to move if space was available. They had one CP move in and another one move to another complex.
Note: If you choose to move, you are on your own. My son was in Vista and his one roomie had to find his own way to the housing about a mile away.
Some people are like Slinkies.
They aren't really good for anything,
but they still bring a smile to my face when I push them down a flight of stairs.
Friends are Gods way of apologizing to us for our families.