There isn't a hard-and-fast rule for everybody. For example, we're taught to shoot double-action with the distal joint, yet I do so with the pad of my finger on many DA pistols. I know a guy who's a crack shot with a 1911, and he uses the distal joint instead of the pad.
In the old days before fancy pantsy lasers, the suggestion was to balance a quarter flat on the top of the slide and find a method of pull that didn't disturb it.
At no point in the trigger pull, however, should your grip or grip position change.
(The forum software doesn't think "pantsy" is a misspelling. Go figure.)
In the depth of winter I finally learned that there was in me an invincible summer.