It is doable but pushing the envelope. If the ship has no customs issues upon arrival, you are in the first group off the ship (self-debarkation), and you take a taxi to MCO, you can be at the airport by 9am or so. I've done it. But just know that something simple like a customs computer glitch could hose you. Royal Caribbean officially suggests the earliest departure flight be 12:30PM.
I agree with Dave. You're pushing the envelope, but you can do it provided everything falls exactly into place; ship arrives on time, no hiccups with customs, there's no problems getting off the ship early, no traffic tie ups, you can get to the airport by 10:00am, and you don't mind paying an exorbitant amount for a taxi (figure from $75 - $100).
Just make sure you notify the Purser's Desk that you want early-off (self-disembarkation) and keep your luggage in your cabin instead of placing it in the hallway the night before. Then be ready to get off about 1/2 to 3/4 of an hour after they dock.
If all goes well, you should be okay.
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