If you believe that some of the mature bucks feel pressure and turn mostly nocturnal, then outside of a hot doe, your best time may be mid day.
Deer must feed (there is always an exception to the rule) every 4-6 hours. If the mature bucks feed before first light and then bed down, they must eat again around noon before they bed down for the remainder of the day. While this theory may not be applicable during all parts of the season, you can see why staying in the stand as long as possible has it's advantages.
