We had an 11:50 AM flight last April, and were at the airport by 8:40 AM with lots of time to spare. But, we were fortunate and did not encounter any traffic delays on the way. We made certain we were off the ship as soon as they allowed us to leave, which was about 7:30 if I recall correctly. (We brought our carry-on bags with us to breakfast at 6:45, and then waited in the lobby.)Then we found a porter who eased us thru finding our luggage and getting thru customs at lightening speed - I would highly recommend using the porter (don't forget to tip, also - this is easy to forget as you are in a rush and they move so quickly - my DH had to run after the guy to give him our tip!)
We also had air thru Disney as well as the transfers, so our luggage was given by the porter to the Delta rep outside the terminal, and our bags were tagged and loaded onto the Delta truck, and we were checked into our flight right there. So, by the time we reached the airport, there was nothing to do for 3 hrs except find a seat, relax and wait! Which was nice as it was the end of April break and the lines were tremendous at the airport.