This is mostly correct, but the team did use it in limited capacities prior to instituting it after home victories in 2007. In particular, I know they used it in the preseason radio pregame intro in 2005; that's the sort of "limited capacities" to which I'm referring, things like intros, promos, commercials and the like. The played it during part of the post-game(s) celebration when they clinched the division in '03 and after Game 3 of the '03 NLDS. Someone somewhere at Wrigley thought of it as a Winning the Big Game song.