Really Good Question,,

At first light I tend to wait out a Gobble that is done on the birds own, this will tell me if there is a workable bird that may respond easyer to the calls.
If it seems to start getting too light and I know I'm running out of low light to make a move , I will use a Locator to see if I can get a strike gobble. This will tell me weather to hang in or maybe head for another location...BT