The room controller is said to assign the rooms 4 days ahead of time but that doesn't mean that the CM's at the front desk do not change things around a little bit afterward. People who check in early may be given a room assigned to someone else who hasn't checked in yet just because it is ready sooner and they checked in first for instance. Or people get switched around due to asking for a different room after initially checking in for various reasons. So while you may be able to call ahead to find out, there are still no guarantees that the room assignment won't change.