You'll see it flash off and the gloss will go away leaving the base with a satin look-give it 20-30 minutes past that point between coats if you can, then let it set a few hours before clear or overnight if possible. You'll get a lot of different answers on this as some painters shoot their base with very little flash times and only 20 minutes before applying clear-but....here's the deal: The solvents need to come out of the base and the clear for full cure and if you rush the flash times they'll be wanting to come out after the clear has kicked and the end result is loss of gloss, less adhesion between the base and clear-sometimes delamination/peeling, contraction of the clear when full cure is reached, cloudiness in the clear. Giving the base ample flashtime will go a long way towards achieving the best results, gloss, durability, timely cure. If you make the clear pass a lot of solvent from the base it ain't going to be happy.
You can do some tests-spray a test panel with base with no flash time between coats then shoot the clear right after it flashes, then shoot another test panel with base and good flash times and clear it the next day- a chip test on both panels a month later shows major differences in durability.