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Wide open question depending on a ton of variables. To establish a cold tire pressure you must establish the correct hot pressure. Whatever you determine that to be, whether experience, manufacturer recommendations or whatever, the easiest way is to assume the tires will pick up (as an example) 8-9 psi from cold. Put your cold pressures at 1 to 2 psi above that. (the reason is that it's much easier to dump psi than to add it) Run the car 6 hot laps, come in, have someone record the pressure and dump it to the correct high psi. Do this a few times and you will have an accurate baseline based on 5..10.. or 15 laps that you can mimic in the future.
As an example you've determined that your tires require 28 psi hot
assuming they will "pick up" 9 psi set the colds at 20 psi
run the car for at least 5 laps, the car comes in at...RF 30, RR 29, LR 28, LF 29. (there's more left hand turns at this track)
record those numbers and dump the pressure to your 28 psi target.
do that as many times as you like, counting laps
Let the tires cool for at least 4 hours, preferably overnight, and record the new cold pressures.
Congrats, you now have a new baseline cold pressures for that track.
Once you get good at that you can project psi according to track and ambient temperatures but first baby steps.