You didn't specify which ship or port but most ships usually start boarding around noon. If you arrive around 11:00 AM you should not have too long of a wait before check in begins. You can arrive earlier but be prepared to sit on the floor in some ports.
If you do arrive between 8:00 and 10:00 you will have to contend with heavy traffic and confusion from people leaving the ship.
__________________ Cruisemates Community Leader/Moderator
"There is a great difference between being well traveled and just having been to many places." ~Me