Everyone is describing TP and some of it's cures.
Dr K says it's a premature hold or a premature release. McDave says it's mental programming. Others have given other opinions on it.
And I think that everyone is right, but only to a point.
I have to go with Al Henderson who described it as your subconscious not trusting the way you've built your shot. And the cure is to build your shot so that you can trust it. Easy to say, but real hard to do.
Often, the better we get at archery, the better we expect to shoot. We've had some success and shot some good arrows and those are the ones we tend to remember. No problem with that. But the problem comes in when we have false expectations of how good we are. Since we've shot a few good arrows, we think that by bearing down a little more we can shoot all good arrows. We start to wait on a sight picture that is perfect, but our form is not quite perfect yet. This leads to hesitation, which leads excess muscle tendion and then to either to flinching or inability to hold. Dr.K's premature release or premature hold.
Mr Henderson & Len Cardinale wrote that you should shoot the blank bale to get the feel of your shot, then use a bridge to ingrain the feel of a good shot on a target. Len recomnended seven drills, one for each major part of your shot, to be practiced every time that you get your bow out. This is the way to build a shot that you can trust. Once you can trust your shot, you are then free to consciously aim and you can rely on your subconscious to not hesitate or rush the shot.
When you can do that, you will have TP under control.
Hope this helps,
Allen