That is correct. You might also want to have MS note that you will be checking in late (and approx time) on your reservation, and possibly call the front desk of the resort the day before.
Have you considered staying in a hotel that first night? If you're flying in, it usually takes longer then you might think to get out of Orlando airport - it took us well over an hour before we got our luggage and were out of the terminal one time when we arrived after midnight. You can usually find fairly nice hotels near the airport, and for a single night of only a few hours sleep, it might be something to think about. Then you just check in to your resort the next morning when you get up; and let them hold your luggage for you.