If my flight does not get in until 11:55 p.m on April 1 and I don't arrive at WDW resort until 12:30 am on April 2, is my check in date April 1 or April 2?
If you are expecting a room when you arrive, your checkin date is April 1. If it were April 2 you could have to wait until 4:00pm for a villa to be ready.
Agree with above posts. Also let them know because the computers usually go down for a short time late at night (early morning). If they know you are coming, they will have your keys all printed. If you don't do online check-in and the computers are down, you'll need to go back in the morning to put on your credit card.