I am concerned sometimes about people who carry semi-autos but refuse to carry them in a ready condition (round in the chamber) as though they will have time to rack a slide in the presence of a close-in threat condition; that is not a good idea when seconds count and your body's adrenaline is giving you tunnel vision and cranking up your heart rate. Nothing wrong with having a thumb safety engaged while in the holster, but it's something you have to practice repeatedly so that your thumb moves on instinct before you level the front sight.
And you're right on about "no warning shots". If the bad guy(s) don't back off and still constitute a mortal threat after you've presented your weapon, your duty to withdraw has expired. Remaining calm and focused is a function of the confidence earned by training and forethought.
The good thing is, most criminal types will quickly disappear and find someone else to prey upon once they see you are armed.
I don't have a CCW,here in Missouri it has been Open Carry since the 1800's. I have opened carried on a couple occasions when my wife had to go into a questionable neighborhood at night. I have a 45 auto(1911)and I can guarantee you my 45 was cocked and locked.