Remember to consider the time difference between your home and port of embarkation. We tested in the U.S. at noon, flew to our embarkation port, spent two nights pre-cruise and will board the ship at noon, 72 hours after testing. We thought that we were cutting it close until we remembered the time difference (since our embarkation port is 9 hours ahead of our home time, we tested 9:00 p.m.).