Your advice is generally spot on, but I have a slight problem with the distance involved here. Not long ago, taking a course in self-protection by firearm, we arranged for one of the younger, fit students to charge, from 20 feet, another one who had a fake gun in his holster. We timed it and found that the "assailant" got to the "victim" in one and a half seconds. The victim did not have enough time to draw and point his gun.
So, if one were to call out "Halt"! at the perp while simultaneously drawing his gun I think he would have a better chance of prevailing.
Dodge the charging assailant as you draw your weapon. Really. To cover that much distance that fast makes changing directions at the point of anticipatred impact nearly impossible, so dodging and drawing prevents the knife attacker from getting a stab or even a clean slash into your vitals.
I tend to on at length about the Tueller Drill, and generally my conclusion is that if you are armed with a gun, you also need a knife in the other hand, as a very short range weapon, to neutralize the Tueller distance.
This is very comparable to the WWI “in the trench, trench warfare” technique of a pistol in one hand and a trench knife in the other; which also extrapolates nicely to indoor domestic combat, since indoors in an apartment or house is effectively the same as an above-ground trench with a ceiling.
Whew. But this being said, the Tueller drill is a prepared, hostile situation, designed to train LEOs. There is very little spontaneity or attempt to deceive. Thus it is an unnatural situation, especially in a civilian-civilian encounter.
Make a mental image of you walking down the street when you see a group of five young black men. One of them approaches you, while walking, not running, saying something to (possibly) deceive you while “closing the gap”.
His effort is to appear and *sound* like a polite person, while getting close enough for a cheap shot (maybe). He is likely not even obviously armed.
One of the biggest clues something is wrong, is that his group are gazing at you intently, waiting to attack until you have been punched.
It is up to your judgment to determine reasonableness, and for most people, this is under five feet(!), just outside of standing, maybe thrusting, punch range. Unless it happens in a bad situation, like at night in a bad neighborhood, you almost have to assume that public encounters are genuine, because you get so many of them.
It is this kind of circumstance where a knife is optimal, because you can discreetly brandish it, handle in hand but blade hidden behind forearm, and if he gets very close, he still likely loses. His cheap shot attempt results in his getting a bad gash or two.
This then is when your pistol comes into play. Once ill intent is established, the pistol is at the ideal range to fend off his companions. You are at Tueller range, and they have no momentum, so they lose big time if they start to charge.
For this reason I obtained a hammerless S&W airweight .38+P revolver. Forget drawing the weapon, fire right through the pocket. Even my best coat is cheaper than me. I love semi-autos, but you can’t get a second shot from inside a coat pocket, and then, after you draw, you have to clear the inevitable jam.