In the wee hours of post dawn, I usually just sit tight and let nature take its course. Nine times out of 10 the gobbling will begin while the Tom is still on the roost without me making a single peep. If I don't hear anyting by decent light, I'll cut trying to imitate a hen pitching out, then yelp a few times. That has worked great for me for decades, but only early in the a.m. Many times crows cawing at daybreak as they come off their roost and start their chater will shock a Tom. I have found that a crow call works fine up into the mid morning and practically all day long, especially when I am working the woods lines. Excited hen cuts and yelps do as well. But for me nothing has ever proven sure fire. So when locating, I might try 2-3 different rackets to get a Tom to gobble. For late p.m. roost locating, I have found an owl hoot works pretty good, especially just after dark:30. However I must admit I have not been very successful in "roosting" birds over the 40+ years that I have hunted them.