Trigger control and trigger finger placement are 2 totally separate things. I don't buy into trigger finger placement. Yes, placing your finger a certain way MAY give you better, but can be different for different folks.
What matters with the trigger is that you press it straight to the rear so as to discharge the weapon without disturbing sight alignment/picture. I can do that with the tip, middle, or choked way down on my index finger. It's HOW I use my finger, not which part of it I use.
Anyone here that has been a pistol student of mine has seen me flip my SIG upside down and pull the trigger with the little finger. Bullseyes all day long at 25 yards and I'll ring steel at 200yds. That sure ain't on that chart!