If you have a good idea where they are roosting and have permission to hunt there, you are golden..
Simply get into the roost area well before daylight, and listen for the birds to start talking at dawn...Sometimes they make a lot of noise, sometimes they only yelp and cluck very softly, but they usually make SOME noise to give away thier position..Sometimes you may just hear thier feathers rustling as they get ready to fly down...As soon as you hear turkey sounds in the trees, walk through the area and flush the birds from the trees, scattering them as well as possible...
After the flush, set up in the same general area , wait a few minutes, and then start hen yelping or kee-keeing.. It can be lots of fun..Sometimes you'll have several birds calling and converging on your setup from different directions..
You can also wait near the roost area in the evening and listen for the birds to fly up, and then scatter them and hunt the area the next morning...Often, however, if you scatter them in the evening, the old hens will often sit up in thier roost trees the next morning and call the poults together beneath them, and then fly down and march off.. I have had much more consistent success by scattering them in the morning..