Like walking under the roost tree. 
After recording for so many years I have found getting set up an hour before daylight will not bust the turkeys off if you are quite. If you know pretty much where they are roosted then try it. Sit absolutely still once the light breaks the horizon. Movement is the only thing that will mess it up.
What I have found is a Turkey has a 30 min attention span under darkness. If you can get to your spot with out much noise, you can walk under and past them. Out of 100's of times I have busted only a few. When a full moon and in an open area.
A lot of times they fly down and game over 
I can attest to that one! The one I recall most vividly was a hunt with my dad as a young boy. He always taught me to crouch down real low as we slipped to our spot (the idea being that even if they saw us, they would think we were a couple of hogs). So, the sun was coming up, I mean just the first tiny spot of light, and BAM; the gobblers flew down directly in front of us, from the tree we were sitting on! I waxed one instinctively and my dad swung his 1187 around and rolled another one over. We never even had a chance to pull a call out! You should have seen the dropped-jaws of our fellow camp members (some of which hadn't even left yet) when we came back with 2 at about 6:00,
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Another one is a story that my dad told me recently, about my great-grandfather. He said my gg was sitting on a tree near his pasture, the sun was coming up, and he hadn't heard a single gobble. Then he felt a big drop of water hit is shoulder, so he slowly turned his head to investigate (it was a dry morning). He looks at his shoulder and is surprised to see not water, but a big glob of bird poop. He then slowly cocks his head straight up, and sure enough, he is sitting at the gobbler’s tree! Rather than let the bird fly down, he decided to use the traditional Mayan method, and kick him off the limb with his old side-by-side.
