R.S. wants you to start the ball ahead of your feet, then shorten your slide step so your foot stops before the ball reaches the ankle area.
Starting the ball ahead of your feet will cause an imbalance at the bottom of the back swing.
I found it much easier to shorten the 3rd of a 4 step, or 4th of a 5 step approach to create late timing.
At the moment of the shortening, the ball is at the transition from backswing to forward swing, so the ball has zero vertical velocity.
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