One of my all-time favorite clips of Donaldson explaining timing.
While the “pullback during the forward move” won’t work for everyone, the concept still remains the same. As the ball is leaving the pitchers hand and approaching the plate, the hitter needs to be making their “forward move” to the baseball.
I like to think of it as having a sight point. You get to that point in your load, and you’re able to adjust your move from there, based upon what pitch it is and where the ball is going to end up. But it is from that point that you see the ball and react to the pitch.
This can be clearly seen in Bellinger, Bregman, and Rendon. As the pitch is leaving the pitchers hand, they have begun their move, are reading the pitch, and adjusting from that position.