The right index thing started when I saw Arnold Palmer do it about 40 years ago when I first started playing so I copied him.
The placement of the putter in front of the ball to the hole line first, then taking my stance started 5 years ago when I was having trouble and averaged 38 to 40+ putts per round. Maybe it was psychological but I swear that one thing has lowered my putting strokes by 20%. I make everything within 10-12 feet.