Re: Time between base coat and clear coat
You need to read the P-sheet for the brand of paint you plan to use. For instance, PPG's DBC/DBI product specifies a time between coats of 5-10 minutes and a "Dry Time to Clearcoat" of 15 minuts at 70F with a maximum of 24 hours.
If you miss the 24 hour window for getting your clear coat sprayed out, you'll need to scuff the base to specs, spray another coat of base and then clear within the 24 hour window.
Other products have different recoat windows. Learn your way around the product sheets for the paint you've chosen before starting the job. Most paint vendors have the product sheets online. If you can't find them, your paint jobber has them at the counter. Many paint failures are the result of incorrect product use and recoat window is an important spec. Missing the recoat window will reduce or prevent the chemical bond between layers and clear can peel off.