Time and TIMING are two different things. A fast draw and first shot on a paper target is not the same as doing it with a real person trying to grab and hit or stab you....
When you are in close contact with the BG you are probably going to get your draw fouled unless you can hit him hard enough to either back him up or REALLY ring his bell. I wouldn't count on that when you are the victim of the ambush.
Moving to better position FIRST (where they can't foul your draw) and then drawing is going to get better results. Paper targets never foul your draw or disarm you. Do it with SIMS guns or airsoft against a live resisting opponent with the BG initiating the action and see how much more difficult it is to just draw, shoot and backup without getting knocked down or getting your draw fouled.
This might be of interest....AAR - 0-5 Feet Gunfighting in Columbia, SC with Randy Harris