The gun should ALWAYS hit the cheek first. This way, you are making sure that the gun is correctly lined up with your eye. All you have to do is look at something and the gun should be already pointing at it!
Remember:
- nose over toes, head forward
- mount the gun using both hands making sure the gun hits the cheek first
- and then lock the gun into the shoulder
Practice in front of a mirror is never wasted!