These guys are correct, but I think you want to know if an area holds any turkeys rather than pinpointing the roost. Sometimes there is no sense in looking for signs or owl hooting if you aren't even sure if the land holds any turkeys.

Start by driving around and scoping fields in late afternoon or evening. They are usually in a large flock this time of year, but should begin to break up into smaller groups soon. Last spring, I counted 88 in one field all together. If you find the flock, you have found the area. It will be easier to find smaller groups later towards the start of the season after they break up. (fields or other feeding areas)

Early April, you should be able to see a few come out and strut in the fields around late morning, early afternoon time frame. By this time, owl hooting works well as well.

If it is a largely wooded area with few fields, you may just have to get out and walk and look for signs. It all depends on the layout of the land in the area you are in. Your best bet would be to read up on turkey behavior and pay attention to the type of land they like. For example, they seem to like pastures and creek beds. They also like a place that has a few rolling hills with a few large trees along a hillside for a roost area. They also need a food source like grain fields and bugs/grasshoppers. There has to be a certain amount of wooded area and/or cover for protection.

This should get you started. Just pay attention to your surroundings and think like a turkey. Good luck.