The position of your body just before impact is important because at this late date in the swing you really have no time for correction. If you’re in the correct delivery position, you’ll hit a good shot. If you’re not, then it’s “scramble time.”
When your hands are thigh high on their way to impact, your lead arm should be extended over your trail arm, which is still bent.
In the photo below, teaching professional John Bierkan is posing in the wrong delivery position to demonstrate what not to do. John has started the downswing with an outward heave of his shoulders toward the ball. As he spins his shoulders, he straightens his right arm, forcing the club out and across the target line. This cutting action opens the clubface, and that spells weak slice.
In this photo, John does it the correct way, starting the downswing with his lower body so that the club slots from the inside. Note the classic relationship all good players exhibit at this point: bent trail arm under straight lead arm. From here he can turn as hard as he wants to and release the two power angles: (1) the angle formed by the shaft and his front arm, and (2) the angle formed by his back elbow.
Tour player Richard Green demonstrates the thigh-high position in this picture taken during a tournament practice round in 2008. His hands are almost to the ball and yet his back shoulder is still waiting to fire through, proof that his body coil is retained until the last possible moment.