Clubhead Lag

Club head lag is the club head trailing behind the hands during the swing. Having the club head lagging behind your hands during the swing is essential if you want to succeed in golf. A lagging club head helps you hit the ball further and more consistently .

The place to feel the lag in your swing is on the index finger of your right hand. This is one of the most overlooked fundamentals is the pressure created by the club resting against the middle joint of the index finger in the right hand (for right handed golfers). This pressure point plays a large role in the lagging of the club on the down swing.
Where the grip falls across the index finger is where we feel the lag of the club. To use this effectively, lay the handle diagonally across the joint of the index finger. During the swing, you want to feel the club's weight in that spot the entire time.

Picture taken from www.golfdigest.com

Cheers
Maurice