footbrake racers
I like to stage shallow at idle, which is adjustable, then bring it up to launch rpm. (Usually between 3,200 and 3,500 rpm - I have a very loose converter.) As soon as I see the last yellow coming on, I hit it.
Any changes to the idle, rpm I bring it up to or tire pressure depend on my reaction times and I change these things to be faster or slower on the tree.
I tune the carb for best response under these conditions. It's important to keep the water temp the same for each run.
Many people bring the rpm's up and edge into the stage beam. But, despite having to hurry so I'm not caught setting my stage rpm while the tree is coming down, this method works best for me.