Quite a few factors here...but for the most part, I would suggest waiting until the next day.
Sometimes on softer slower drying clear, you will need to rebuff a few days later since it was not "fully" cured.
also wouldnt wait too long. the next day is perfect. UC 35 is a high solids clear making it more difficult to buff to start off with. if using HOK clears it is recomended to final clear with UFC 35 becouse it flowes nicer and buffs a hell of a lot easier than the UC 35.