I wouldn't worry about spooked birds abandoning an area. Probably 100% of turkeys in Iowa have seen a human at one time or another. All you've done is educate them a little bit. Hopefully you havn't been calling to them at all. When scouting don't call, just listen and try to follow or observe the birds from afar. Some birds'll fly up earlier than others. Usually within the last half hour of light is when they hit the trees. If you can locate where they're roosting try and sit where they fly up from off the ground. A lot of times a bird will land and take off in the same general area. Now don't go trompsing right up to the roost tree cuz you'll spook them and they'll fly a half mile before they land. Turkey hunting requires patience, lots of it. If you can get a more experienced person to help ya out a bit that'd be good, otherwise keep asking questions in here, we'll try and steer you in the right direction.
good luck!!