Well, not so fast. What you provided only discusses the "step back" from the pitcher's plate. What about the "start back" where the pitcher is no longer required to have her non-pivot foot in contact with the plate while taking the signal? That's what virtually all sanctions, including NCAA, now allow.
These are just my local area rules. But my gut tells me that the wording "You can step back during, prior, after, whatever the hell you want" is their way of saying we don't give a crap about that foot -- do whatever you want.