Make your normal backswing then slam the toe of the club into the sand. And I mean slam it! Once you feel impact loosen your grip pressure allowing the club to rotate in your hands to a squared position.
Stop your backswing when the top of your right wrist is about three inches below your belt. Hinge your wrists slightly so that the shaft is a few degrees above parallel to the ground when you end your backswing.
When you look like this you know you’re synced. Even as I strike the ball my overall posture and physical state is relaxed and my grip pressure is light. This frees the clubhead to fully accelerate through the ball for maximum backspin.