Trip to Port from MCO was 30-40 mins. I dont remember exact times but we had 1st seating for breakfast on departure day from the cruise, we were also in the almost front of the line when they let people off the ship and out to customs and baggage claim. We had a van from the Radission waiting at the lot to bring us back to the Radission where our rental car was waiting for us. After loading the rental car up with family and luggage, stopping at gas station for a few minutes we drove to the VWL in the Magic Kingdom resort area and was checking in at 10:00-10:15am.
If your uncomfortable with your time that was re-assigned ffor your flight - get on the phone and "ask" if there are other flights you could be re-assigned to (throw in the fact that you selected the original flight for this very reason due to the time of the cruise and travel back to the airport) I dont know where you live and what airline your using - they may or may not have any flights to do anything for you. If they do - I would not expect them to charge the "iternary change" fee for the change they made. Always be polite and if you get someone who is not going to help you, say thank you, hang up the phone and redial. They have more than 1 operator and I always get someone who can do what others have claimed could not be done by anyone.
Good luck! and enjoy that Cruise!