There is no correct answer.
Dealerships only do two coats, and car is delivered the next day.
If the car is a restro or a show car where you might have 3 to 9 coats of clear, then you want it cured enough when bolting on, say a door handle, you dont move the clear.
Personally, at home, I would give the car a week in the sun and never have had an issue.
Overkill perfaps, but I never do less than four coats of clear.
The only help I can give you is every job is different and 2 or 3 days in shop can wor,k but time is on your side.