Disney recommends no flights before 12:30 pm. I suspect their years of experience show that that is the earliest average time that folks all make their flights. Yes, some folks make earlier flights, but when Disney says nothing before 12:30, there must be a reason.
We barely made our 12:35 flight, even though the Magic started lettling folks off at 8 am. There was a 45 minute wait to get off the ship, so we didn't get to the airport until 10:15 am, PLUS there was a 90 minute wait to clear security at the airport. Our flight was already boarding when we made it to the gate.
Disney wants everyone out of their cabins by 8, and off the ship by 9, but I ran into some folks at the airport on our cruise who were among the last off, and it took until 10:15.