Question about a straight front leg at impact

[2mongoose]

As I continue to work on my pivot and manipulate the club with it instead of my hands I find myself confused about the idea of a straightening left leg (I'm right handed) at impact.

When I get my left hip going out towards the left and rotate around my spine to keep some axis tilt, when do you "feel" your leg straightening? How much should it straighten? I'm afraid I'm "soft" at impact or just slide and block it right.

Here is Luke in this month's golf digest for some reference.

 

[Brian Manzella]

Ideally....

It would straighten when the right arm does.

But, the feel is that it is sooner—for some.

You GET OFF your left foot on the backstroke, ON your LEFT FOOT to start the downstroke, AND OUT OF YOUR LEFT FOOT to get your left shoulder up and hit the ball.