A firearm is not a shield? I think Smith and Wesson disagree. (M&P Shield... haha)Ask for legal advice from a Lawyer, not on the internet. Therefore any following advice is just my opinion, not any sort of legal advice.
Reconsider your mindset.
A firearm is not a shield and should not be thought of as a deterrent (though it sometimes acts as one, depending on that effect will get you into some serious trouble). It is unwise IN THE EXTREME to use a firearm, or even the hint of one, to "warn off" a potential aggressor and the introduction of a firearm into ANY confrontational situation is ALWAYS an escalation.
Valid use of a firearm in a self-defense situation is pretty much restricted to determining the answer to the question "do I currently have a reasonable fear for my life?" which is often determined by an analysis of the "MMO" yardstick.
Means - Does this person have the means to harm me?
Motive - Does this person appear to have a motive?
Opportunity - Can this person actually get to me to carry out their threat?
If the answers are yes, then you are past the "warning" stage and it is probably time to defend yourself. If any of the answers are "no" then introducing (or hinting about ) a firearm is generally a bad idea.
The people who say that if you pull, you HAVE to fire, are wrong. You can't just go into autopilot and start blasting away. Clint Smith's "say stop while shooting" seems silly to me. You should have said that before, give that a shot at de-escalation. If pulling your gun causes a submissive response, don't pull the trigger. Back away and leave. The idea is to avoid the hassle that comes with a shooting. As far as being charged with brandishing, get real. Are you going to sit there and wait for an hour to see what comes next? Leave.