You know you must hinge your wrists during your backswing, but you're not sure when.
For full swings with your mid-and long irons...
Simply maintain the hinge that you established at address during your takeaway. Full swings require a longer body pivot, so hinge less and turn more as you bring your hands to waist height. You know you've done it right if your chest points away from the target and the butt of the club is outside your right leg when the shaft is parallel to the ground.
For half-swings with your wedges...
Finish your hinge before your hands pass your right knee. Short swings from 30-60 yards require much less body pivot, which means your wrists must hinge sooner in your backswing. You've done it right if your chest points at your right foot and the butt of the club is on top of your right leg when the shaft is parallel to the ground.
For half-swing shots inside 50 yards, your right wrist should hinge before your hands pass your right knee.
Don't do this!
Error on the quick side You've been told to keep the clubhead low in your takeaway, which is good advice unless you overdo it and remove the hinge in your wrists that was established at address. Now you're late on your hinge going back, which means you'll be early on your hinge going forward and you'll hit the shot fat. As a general rule, hinge your wrists sooner and you'll hear the sweet sound of crisp contact more frequently.