You can locate without calling. And that is the right way to do it. IMO. You can use crow or owl calls but no turkey before the season.
Try to get out therebefore daybreak and listen. Rightbefore it gets dark listen again as they will gobble when they go to roost. Not all the time but most of the time. If you do not hear any give an owl hoot or two in the morning (right before daylight)and follow it up with some crow calls after it lightens up a bit.
You can walk through the area and scout for feathers etc. during the day. If you do bust some they should not move out of the area, they willsimply avoid you for the day.
Find out where they are feeding and drinking by driving the area and glassing from afar. This should give you enough info to get started when your friend gets there.