You have to be able to carry everything off the ship unassisted. No requirement for an early flight. One caveat - on my last RCI cruise they were quite adamant in telling everyone planning to do the self-debarkation that only small pieces of luggage (carry on) were permitted. They said Customs was taking a dim view of those trying to muscle big suitcases off the ship. It may have just been the Port Canaveral staff. However, my observation was that they got compliance and thus there were no log jams.