Personally it would seem a very unnatural movement to extend your finger forward to the front trigger after you have firmly clutched your grip and right hand pulling the stock to your shoulder and got whacked with 60-90 pounds of recoil.

It would seem a more natural biomechanical movement at speed to go front to rear with your finger,flexing the finger vs groping forward to hit the front trigger guard, then come back and risk ?slapping the front finger and risking a premature shot.

Obviously rear trigger first can be done with practice but minimally sliding your grip and forefinger back to the rear trigger as your right arm pulls back and your body comes forward recovering from recoil seems a much more natural fluid movement to me.