I normally carb an already cold keg (32F) over about 24 hours at 30 psi and it does the trick for me. I kegged a beer last night but will be gone until Sunday. Any ideas on what pressure I should keep it at to get it carbed by Sunday afternoon/evening? I have it set at 20 psi as a guess.
24psi for 48hrs at ~38F generally gets me to 85% carbonation. I think an extra 24 hrs would put me slightly overcarbed. Perhaps 20psi for 72hrs would get you to ~85-90% carbed. I don’t think you’d be overcarbed but you may still need another 12-24 hours to finish getting up to perfect carb level. At least from my experience this is how I’d approach it.