Is it possible to board a Carnival cruise before embarkation time?

We will be cruising on Carnival Triumph on April 5th and the embarkation time according to Carnival is 12:30pm but I was wondering if it was possible to board the ship before this time. If it is possible please tell me how early can I arrive. I cruised with Royal Caribbean once and the boarding time was 12:30 but we arrived at the port and boarded the ship around 10am.