Disney considers anything before 12:30pm "early". I'd leave your flight where it is.
We BARELY made our 12:35 pm flight. Literally walked from security to the gate onto the plane.
Biggest problem was there was a 90 minute wait at Orlando airport to clear security. We got to the airport at 10:15 am.
Also there was a 45 minute wait to get off the ship....not sure why, there was a steady flow off, just a slow flow. Once in the cruise terminal it took less than 15 minute to find our luggage, clear customs/immigration, check our bags with AA at the port, board the bus, and be on our way.
Disney does want folks off by 9 am, but talking to folks at the airport, it took Disney until 10:15 to get everyone off. We had late breakfast, at 8 am, and when we came downstairs at 7:45 people were already getting off the ship, like I said, it was just a slow steady flow.