Welcome to the forum!
Also - congratulations. Overall you did right. You were in a bad situation, you got out without getting hurt, nobody else got hurt, and no legal entanglements. Well done.
+1 to keeping your gun fully loaded (i.e. one in the chamber, full mag inserted), and close at hand. Sounds like you got that message.
When you ask if you could have taken action before your window was broken, it sounds like you mean using your gun in some manner. I think The Annoyed Man provides the most direct answer to your question. You have also gotten advice which consists of a mixture of legalities and tactics and so forth, which sometimes clouds the actual question and issue at hand.
I find it helpful to think of these situations as operating on three levels simultaneously: the legal, the tactical, and the moral. It is a happy day when you can get your action to meet the requirements of all three levels simultaneously. Actions that are legally and morally sound (stand your ground) might not be tactically wise. Things that are tactically advantageous might not be legally or morally justified in a given situation. When you are what-iffing and war-gaming various scenarios, it might help you to figure out the best options if you break them into their legal, tactical, and moral components. At least it helps me.
I don't know if you are aware that the very first CHL-involved shooting in Texas was a traffic event right after the law came into force. You might find it interesting to compare notes (and value the wisdom of keeping your window rolled up). Documented details are hard to come by now, not least of which is because the anti-gun forces immediately used it to try to squelch Texas's new CHL program. Newspapers deliberately underplayed what happened, calling it a "minor traffic accident" and "scuffle" and so forth. As far as I have been able to determine, the details are thus:
The new CHL law came into effect on 1 Jan 96. On 21 Feb 96, Kenny Tavai clipped a mirror on Gordon Hale's vehicle, a pickup I think, but did not stop initially. Hale followed and got a license plate number. When both vehicles came to a stop, Tavai walked back to Hale's vehicle. Hale rolled down his window expecting to talk to Tavai. However, Tavai yelled at Hale, then punched him through the window several times, by some reports breaking a cheek bone and detaching a retina in Hale's eye (altho this is left out of the vast majority of newspaper articles). Tavai then grabbed Hale and tried to drag him out of the vehicle. Hale came up with a pistol, usually reported as a .40 caliber, and shot Tavai once in the chest. Tavai died from the wound.
The Dallas police arrested Hale and the DA charged him with murder. A grand jury declined to indict him. The VPC was sad.
