I had a older turbo Probe Gt years ago (fwd). I would hold the r.p.m.s at about 2500 - 3000 and would let the clutch out about 3/4 on the way when the light dropped. Then I would let out the rest of the clutch depending on the launch / tire spin. This is basically what everyone else has mentioned here. Tire psi. is critical as Mr. Self Destruct noted. Dont go to low though because that will work against you by having the sidewall of the tires being to soft. It will also cause your car to walk around on the track at the top end not to mention to low of a tire p.s.i. = more rolling resistance which equals a little less e.t. and trap speed.