A lot has to do with the natural align of your hip-leg-foot. If the foot turns out a little when you walk or run then you're probably going to have the same thing in your push off. However an early turn out can lead to poor lower body mechanics and an excessive dragging of the foot.
Turning the shoulders early is a lot more common than you would think. When you slow down a pitching motion, at 3 o'clock, a lot of very good pitchers have the glove arm out further than the throwing arm, meaning that the shoulders are open. I generally discourage it but since it is common I don't insist. You can see it in the Rachel Garcia clip.