Been on 4, and to us the best time to arrive is 11:45 to 12:00.
Boarding is just about ready to begin, started at 12:00 on 8/9. When we entered the terminal the counter lines were empty, walked right up. By the time DH arrived back all he had to do was show his ID and we walked right on the ship, 12:20, no line there either because the long line was through. The first rush is over and for us this is the best. 1st cruise arrived too early 10:45 too long a wait, 3rd cruise too late 1:15 ate too many shrimp and was not hungry for dinner. 2 cruises at above times were just right.