I read your approach with interest, because I have been down the same path. Your shot sequence seems to build a solid foundation for the shot, with or without any consideration of target panic.
Don't overlook the fact that target panic is primarily a mental issue, and to continue the analogy, no matter how solid the foundation for a house is, it isn't going to keep the termites out unless you do something specifically about the termites.
I have taken Joel's and other programs to deal with target panic, where target panic is defined as the subconscious mind taking over the shot, with the cure being to reestablish control by the conscious mind. I have come to believe that this concept is flawed. I don't think the problem originated with my subconscious trigger, which I have re-adopted and seems to work fine, as it does for the great majority of traditional shooters in the country. I think the effectiveness of all existing programs to treat target panic lies with their emphasis on increasing concentration skills, although they don't focus enough on this process.
As an example, Joel's emphasis on focusing on the tiny movement needed to activate the trigger is a concentration skill. I say let's do away with the red herring of the subconscious, which nobody really understands anyway, and focus on the real solution, which is increasing our abilities to concentrate.
Increasing our concentration skills means increasing our ability to eliminate distractions, no more, no less. Target panic is caused by a distraction of some sort. Examples of distractions include a fly buzzing around your head, but also can be disjointed thoughts, emotions, and images floating around in your brain. We may not even be aware of most of them because they are such a normal part of our lives. But becoming aware of the specific distraction that is compelling one to release the shot before one is ready to shoot it is the first step toward learning to eliminate it.
For example, my own target panic was triggered by the knowledge that I was drawing the bow with the intention of shooting it. You appear to have the same problem, and your solution of not deciding whether to shoot until a certain point in the shot sequence is a form of concentration, because your decision cannot be casual or your brain would just override it; it has to be a deeply held conviction to work.
In my case, the knowledge that I was drawing the bow with the intention of shooting it triggered an emotion, which was the anticipation of the shot. Emotions are not expressed in words, but in this case was a combination of an exciting vision of a great shot combined with anxiety over having a bad shot. These conflicting emotions were the distraction that was triggering the early release of the shot. Once I recognized this, I could become aware early on in the shot sequence when these emotions occurred, and could eliminate them through increased concentration, by finding a quiet, blank place in my mind where these emotions didn't exist. This is not the same thing as staying in the same part of one’s mind where they do exist and trying to ignore them. If I can't find that quiet place, then I can let down the shot and start over.
Learning to concentrate at this level is not as easy as reading the words, but once learned, is very effective.