I was messing around with my forehand recently, trying to imitate a Wawrika video I saw - I was trying to get the turn the doorknob thing with total relaxation. I found that if I think "lead with the wrist" it happens by itself. The part of the wrist that I feel is leading would be the ventral surface of the wrist (or the inside). The main advantage may be in emphasizing racket lag and a relaxed wrist - leading with the wrist seems to mandate correct form. Watching these slow motion Federer forehands makes me think I'm onto something - works for me at least.
https://www.youtube.com/watch?v=OKtZudSpFMg
https://www.youtube.com/watch?v=OKtZudSpFMg