Ideally there is no lateral movement of the hips. But who among us has an ideal swing, right? Harvey said (and that's good enough for me) that if you move at all, move behind the ball, in other words, back. It's still bad to do that because then you want to "lateral" forward, which a lot of people do. The one main thing you cannot do is lateral past the ball or ahead of it. The hands don't have time to catch up. That's why you hear the term "stay behind the ball". If you keep you hips centered and pivot instead of sway, you'll be much more consistent...you can then fix a block by moving the ball forward a little in your stance or fix a smother by moving it back.
As always, let us know how you're progressing. Love these late-night sessions...lol.

Shade