Hi,
you have to be off the ship by 9 a.m.
The port is about an hour from the airport.
I dont know if you are renting a car, or taking DCL buses or what, but if traffic is moving ok, it will take 60 to 75 minutes to get to the airport.
I guess with check in and all I would say have your flight booked for 1 p.m. or later to be safe.
Hope this helps a little.
Kathleen