The NCAA tournament will get started with the First Four games on Tuesday, March 13, but most bracket challenges do not lock until tip-off of the first game of the Round of 64, which will happen around noon on Thursday, March 15.
Since the inception of the First Four games in the 2011 tournament, at least one of those teams has won a Round of 64 game, three of them have reached the Sweet 16 and in 2011, 11-seeded VCU reached the Final Four, so it will be crucial to pay attention to those matchups if you want to optimize your bracket.