This is Johnny Miller's view from 1976. Not claiming it is correct but may be of interest to some.
. . . most of the wrist cock is done early in the backswing, there is a tad more wrist cock at the top.
And yet today, the 2010 version of Johnny Miller -- from the tower atop the 18th green at Riviera and the Northern Trust Open -- extolled the late wrist cock of the Champion, Steve Stricker, and proclaimed his swing (loosely quoted) the one "we may all be copying in the future".
My how things do change.
Geometrically, the Snap Load [late Left Wrist Loading Action] is most efficient.