In most ports (including those in Florida) I would never consider booking a flight much before 11. But Barcelona would be the exception. The authorites in Spain do not usually delay clearing ships (the US ICE folks could take a lesson from that) and assuming your ship docks on time, you should be able to debark by 7:00 (even earlier if you wanted to carry your own luggage). If you grab a taxi, you will be at the airport in about 20 - 25 minutes. If you take the cruise ship shuttles, you will pay more, wait more, but the drive will be about the same.