The time you get on the ship depends on the debarkation of the previous cruise. It can vary by more than a hour. Usually any time from about 11 to Noon, but I got to the port once at 10:50 am and everyone that had arrived was onboard.
There is no set boarding time.
Conquest 7/21/13, Miracle ALASKA 8/27/13, Miracle HAWAII 9/17/13, Celebrity Summit, 11/30/13, Celebrity Summit, 12/7/13, Celebrity Constellation, 2/7/14, NCL Epic 3/2/14, Allure 5/4/14, Allure 11/2/14