Set the trail elbow under the trail shoulder
Porzak shares the checkpoint he uses with all of his golfers: at the 'set' position — partway into the backswing where the club is set — look at the trail (right) elbow, and it should sit directly underneath the trail (right) shoulder. It is offered as a simple, repeatable position check for where the trail elbow is at that point in the swing.
Channel: PorzakGolf
Watch official source at 3:48