Put a paper turkey target up at 30 yards and shoot at it. Once you got you pattern dialed in, move the target out to 40 or so and see how you shoot at further distances.
Buy some cheap shells to get close to the target and then use the shells you plan to hunt with or test. If your not hitting the target at 20 or 30 yards,bring it in closer until you hit itand work back out.
Start close with trap loads to get the scope dialed in, then move to 40 yd. with some turkey loads. Keep in mind that if your scope has 1/2 min. click adjustment, it'll take 8 clicks to move the POIone inch at 25 yd. If it has 1/4 min. clicks, it'll be twice that.