The short answer: get every coat on within about an hour, or wait at least 48 hours. The gap between those two is not a safety margin, it is the period where the surface has skinned over while the paint underneath is still soft and releasing solvent, and a fresh coat’s solvent attacks that half-set film and wrinkles it. Manufacturers print both numbers on the can and almost nobody explains why there are two. The practical consequence is that you should plan the whole job before the first press: light coats every few minutes, enough paint in hand to finish, and no interruptions. Running out of paint halfway is how most wrinkled projects begin.
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