In my biased opinion, I believe the key action of ensuring one is "laid off at the top",
is to rotate the forearms clockwise around each other during the backswing.
Try this at home, take an imaginary club in your hands and address an imaginary
ball. Start your backswing in slow motion (that's why I chose an imaginary club)
and rotate the forearms clockwise around each other.
Stop when one's shoulder is either at ninety degrees or less depending on one's flexibility.
Turn your head to the right and look at your hands and which way the imaginary club is pointed.
It should pointing to the left of the target. From that position, rotate your forearms around each other counterclockwise, examine your hands and where the imaginary club is pointed. It should be across the line.
I tried this with a real club on the driving range and it seems to work quite well.