Sorry to influence the young with my bad practices, I started shooting a long time ago and watched movies with John Wayne and never saw him with the finger outside the trigger.
Is obvious that you don't believe that my MAG 951 is brighter than the Surefire M-6.
See if these pictures taken at fifteen yards from the tool shed with the camera in the tripod and the lights coming from 43 yards away will please you.
Surefire M-6 500 lumens
MAG 951 II (951 lumens)
Shoot three times, one center and one to each side, he could be aiming in a Chapman or Rogers-Surefire or Harris etc. right at you and the center hold will be valid. The ones to the side are just in case he is left handed or right handed in which case the positions of the pistol and flashlight will be reversed
I don't like to paint scenarios and get my imagination to play with them; if you are not trained to react under stress a certain way it is very unlikely that you will remember what to do in any of the hundreds of variations in gunfights.
Just do your best.