Boarding time always depends on how quickly the cruise line can clear the ship after the cruise that just came in. Sometimes there are circumstances that prevent early boarding, like an unannounced Coast Guard inspection or problems with a departing passenger's passport. Also, since the Allure holds so many passengers, it sometimes takes longer than you'd think to clear the ship.
That said, it could be that boarding time will be earlier than 2pm. I've known people who have boarded as early as 11:30am or noon. There's just no way to know in advance. My advice is to get there early and whenever the ship is cleared, you'll be good to go.