I did a Tueller drill with a dummy mounted on wheels on a pulley system at a practical shoot. I was second in line so I only got to see one person run the drill before I went. I was openly carrying my Glock 43 in an IWB holster (meaning no cover to sweep away).
The guy who was pulling the dummy purposely tried to distract me by asking if I knew the drill. As soon as I turned my head towards him, he took off. Fortunately, I had a friend filming me running the drill so I could analyze my performance. It was the first time shooting the Glock 43 and I was pretty happy with it.
I reacted pretty quickly to him taking off. By the time he got 2 steps away, I had the gun clear of the holster. While the iPhone allows me to scroll through the video slowly, it only shows time in one second increments. I was able to draw and fire 2 shots within 1 second, then I side stepped and made a headshot in less than a second. The dummy had moved nearly half the distance by the time I got the first shot off.
Breaking it down into frames (iPhone records at 30 frames per second), my first shot occurred about half a second from the draw. I can count 7 distinct frames between my first and second shot, which works out to .23 seconds. The 3rd shot, which involved a sidestep took another .5 seconds. The dummy was about 6 feet from my position when I took the last shot.
My first 2 shots were a little high and left of center. There were 4 inches apart and hit the area between the right pectoral and right shoulder. The second shot was right above the ear.
While I'm sure I could have done better, I was pretty happy with my reaction to the guy taking off on me unexpectedly. It was also my first time running a drill like this. It was also the first time shooting that gun so point of aim may have been off slightly. Overall, not bad for a first attempt. By the way, this was somewhere between aimed fire and point shooting. I picked up the front sight and did a double tap, and then picked up the front sight for the head shot.