When I first started out in open, I would think about going slow and steady....shoot a good first stage to start the match.
As I have learned more about the mental game, I have come to the same point, though not in skill , as BE....10% mental slow down. For me, viewing the first stage mentally as if it was the last stage of the match keeps my head in the right place to just shoot it smooth and as fast as the sights allow.
When I hear a new or inexperienced shooter say "Oh, I never have a good first stage", I will take the time, if they are receptive, to discuss the mental game and coach them on how I handle it.