This figure will depend on a number of factors, there is no pre determined launch RPM as there are a number of factors, tyre temp, road condition, car spec etc,
For example my old tuned gt needed 5000 on the clock or she stalled as the torque band was moved right up, 5750 on the clock and she lit the wheels like a catherine wheel!
This was one of the reasons I sold up, as coming home from the clubs at half four 'launching' to get up the driveway between our, and the neighbours house didnt go down well lol!
Ive found if im trying to take the lights in my Pug Partner van, im nigh unstoppable at 3000 rpm lol!