What is the minus number that you count down from in the beginning of a run if you press START GAME and SPLIT at the same time on PAL version?

If that made any sense.

for example = -3.21

I think -3.42 will be the most accurate. Although keep in mind that you have to start the game as soon as possible.

Someone double-check my numbers, but according to my calculations, the amount of time between the start press and the frame that "400" appears at the start of 1-1 varies from 2.76 to 3.10 seconds, depending on exactly what frame you press the button. If you press it on the first possible frame, then -2.80 would do it.

Personally, I would just either start the timer at 0 and start when the level starts, or use -3.46 (plus any multiples of 0.36 if you need to wait on the title screen for whatever reason) and start the timer from reset.