As any amateur Jedi, wannabe wizard, or die-hard Twihard could tell you, opening-night midnight screenings are a rite of passage. But that could change now that studios are expanding their definition of ”opening weekend” by premiering blockbusters (including Iron Man 3, White House Down, and World War Z) on Thursday evenings instead of the traditional time of 12:01 a.m. Friday. The adjustment isn’t only affecting the moviegoing experience, it’s also shifting box office numbers, since studios are now including Thursday grosses (rather than Friday-through-Sunday numbers) in their ”opening weekend” totals. The move is a bit misleading, says BoxOfficeGuru .com editor Gitesh Pandya: ”The bulk of a day’s business is made after 6 p.m., so [Thursday’s] really a separate day’s gross.” Even movies meant to open on Wednesdays are getting early starts. Warner Bros. opened We’re the Millers at 8 p.m. on Tuesday, Aug. 6, giving the Jason Sudeikis/Jennifer Aniston comedy three nights of play (and positive chatter) before the weekend. The strategy paid off; although Millers didn’t open in first (Elysium did), its Friday-to-Sunday gross was $26.4 million, and it’s now made nearly $70 million. Dan Fellman, WB’s president of domestic distribution, says the early opening wasn’t meant to inflate numbers, but to build word of mouth. ”Why not open up a little early and let the audience talk about the movie?” he asks.