OK, so as soon as you turn off the heat gun or hair dryer, whip out the primer spray can and get to work. Read the labels, of course, but I think you've usually got 48-72 hours after the primer dries to get the first coat of paint on. After the first coat's on, you can continue or come back and hit the previous coat (that you left to dry for a week or two, I know how that goes!) with a light touch of 1200 abrasive to roughen the surface before the next coat.