Oil temp (in my educated opinion) is the best thing to go by to tell when your car is warm enough for WOT pulls. Too many engines get hurt/worn due to excess load when too cold. IMO, wait until your oil is ~150 degrees before heavy boosting. In my Evo, it takes the oil quite a bit longer to get warm than the water. I’ve never timed it, but it’s probably 3x as long.