You’ll never know until the day comes.
Training and more training..
One of the major reasons I train almost daily in Escrima(Filipino Martial Arts - FMA) is that in this martial arts style you start training with weapons and then move on to empty hand training (most martial arts styles are the opposite).
So how is this relevant to firearms carry?
I'm glad you asked that question...
Distance is time, and time is distance. Time gives you choices that pure reaction does not.
We all can't afford to pay for high tech training of reflexes but there are alternative inexpensive methods of training that people in the Philippines and other low income countries have been using for many, many, years.
Rubber training sticks are cheap and don't hurt that bad. So buy a pair and have a trusted friend/relative stand about 10 feet from you and attack you with a rubber stick while you attempt to deploy your unloaded firearm. You'll find out pretty quickly how even simple movements are difficult under duress.
I've had students fall on their asses as they tried to retreat from me swinging a rubber stick at them. It's hard enough to create distance without falling on your ass or stumbling just trying to avoid getting hit by the rubber stick. It's even more difficult to try to draw a concealed handgun as you're creating distance.
I have all kinds of drills like this one that I practice pretty often. One of them is called "Mother in Law"...
That's where we do a scenario and your adrenaline gets going and the situation changes where lethal force is no longer needed. A designated person in the scenario yells "Mother in Law" and the student who is defending themselves has to stop their self-defense. It's not a perfect drill but the purpose of it is to prepare to disengage from a conflict once the threat(s) is no longer a threat.
One of the hardest things once you get going, is to disengage. It's also difficult to keep your emotions in check. But with all the camera phones and cameras out there, there is a possibility that every one of your actions will be scrutinized by people who couldn't fight their way out of a paper bag.
The more you do these types of drills and add variety the better chance you'll have to not overreact, not pee or poop in your pants and use a minimum amount of force (perhaps avoid deploying/brandishing a weapon) that wasn't really necessary but your fear and reaction caused you to deploy.
Train your body. Train your mind. Keep movements simple(practice short steps front, back, and to either side). Keep moving. Be aware of your environment (especially the exits). If you fall or stumble get your ass back up and keep going. If you get hit or stabbed(we also train with markalots and rubber knives) keep going. It's about survival not style points...
And most importantly, don't forget to breathe...