I don't think they will give out a room number until the room is actually ready for your occupancy. Even if you check in at, say, 11am, they won't give you the number until it's ready.
If you want a certain section, floor, location, etc., you can make the requests known when you make the reservation. If something is really important, then I believe you can call the resort 1 or 2 days before you arrive.