7-1 Shift and False Start
ARTICLE 2. a. Shift. After a huddle (Rule 2-14-1) or shift (Rule 2-22-1)
and before the snap, all Team A players must come to an absolute stop and
remain stationary in their positions for at least one full second before the ball
is snapped, without movement of the feet, body, head or arms (A.R. 7-1-2-I).
There is no reference to when this complete stop has to take place. If A has met the requirement, then they can snap the ball as soon as the ball is ready for play. The ball is ready for play when either the ball is placed on the ground and the official moves to his position or when the R sounds the whistle. Therefore, your knowledgeable and reputable source is correct!