Can you come in the night before and take ME in the morning? I don't have enough points to stay at Disney the first night, however I do have enough Hyatt points to stay at the airport for one night then take ME in the morning. Has anyone done this? Is it allowed?
TIA
Yes. It is allowed.
Disney's Magical Express (DME) is a function of your Disney resort hotel stay, not of your flight. You are allowed to use DME on (or after) your resort check-in date to travel from MCO to your resort.
It doesn't matter how you arrive at MCO. You can arrive on a flight, or you can arrive by elevator from your MCO Hyatt room. Or you can arrive some other way. (I've arrived by rental car after spending a week elsewhere in Florida.)
You are still required to have a DME reservation to use DME.
Most people arrive by air, so that's what they normally ask for when you make reservations. But you can also just give them an approximate time that you want to leave from the airport.
The only question becomes how to handle your luggage. You would not apply the yellow DME tags at your home airport. You would claim your bags at baggage claim at MCO and take them to the Hyatt.
I've read reports of Hyatt guests attaching the yellow tags the next morning, providing the bags to bell services, and having the bags "magically" delivered to their Disney resort room. (Presumably, you would tip bell services at the Hyatt, but DME would eliminate the expectation to tip bell services at your Disney resort, if you use the yellow tags and allow DME to handle your bags). But I have no personal experience with this. If that still works, it would be a great convenience. I would ask bell services at the Hyatt.
