If you are at Port Everglades the airport is only a few miles away whereas Port of Miami is I believe 25 miles. Frankly you should have no problem with a 12:30 flight. RCCL will disembark according to flight schedules 1st. Those who drive (me) always get off last. They have give you tags the last night and that is the order that they go.
Golden Princess 12/04
Enchantment of the Seas 4/02
If you have a cruise leaving from Ft. Lauderdale, it should be no problem, the airport is right next to the port. If from Miami, a little longer time to get to the airport, but I'd forget the cruiseline transfers and just grab a cab and you should be fine, just let the cruiseline know you have a flight at that time and you should be able to get off the ship in time, good luck. So, what ships are you looking at?
Sorry to mention this. Although I agree the timing would most probably work, when we were booking our air for March we called RCCI & they said they would not guarantee that we would make it in time, as air passengers have to be at the airport long before the flights. Our travel agent also mentioned that if one bag was late in being hunted down at disembarkation we might not get there in time. To avoid the stress, we went with an evening flight & will have to impose on local rels to entertain us or take an excurison that ends at the airport.
We have been on 2 cruises with RC and both times when we woke up that morning we were already in port. We were at the airport (Orlando and Ft Lauderdale) in plenty of time to get an earlier stand by flight to Atlanta. I would not advise any earlier that 12:00just in case of delays. Orlando is about an hour drive from Port Canaveral. Also you can put an earlier flight time on your sheet the night before and you get off earlier.
The airline you fly also plays into this as some (Northwest) say you are to be at the airport 3 hours before departure time; however, I think the advice you have been given here is really good - your port will be the most significant thing to consider in making your air travel plans.