User blog comment:B214/Season 3 confirmed!!!!!!/@comment-24910433-20150306235329/@comment-16281343-20150307004127

@Gary

Are you talking about this?

"「ハイスクールD×D BorN」先行上映イベント

・日時 3月15日（日） ①15:15開場 15:30開演 ②17:45開場 18:00開演"

If so, then that's not what you think it is.

Just like in any movie theaters, there is a time where the gates are opened and time where the actual movie starts. In the case above, the gates open on 3:15PM then the screening starts on 3:30PM. A leeway of 15minutes where given to people to come inside the theater.