Originally Posted by The Situation

Boarding time almost always begins later than it states on the boarding pass. The airline will state an earlier time to ensure everybody is at the gate and ready to board when boarding actually begins to avoid delays. If boarding begins later than it states on the boarding pass, do not take this to mean that the flight is delayed (I have overheard a lot of panicked infrequent travelers worried that the flight is delayed..."my boarding pass states boarding begins at 12:15, but its 12:25 and we haven't started boarding, why are we delayed?" No reason to panic, you will still depart on time (or even early) in this scenario.