Pulling through is not something that you do. It's a result of setting up the shot with the most stable muscles and those are in your back. If the only muscles holding back the pull of the string are your back muscles, the pull through or follow through will happen while you are focusing on what you want to hit.
Sorry that I'm not a good enough writer to explain this too well.
It's a pretty fine point between making something happen and letting it happen, but it is important to a good shot.
There should be two parts to every shot. The first part is drawing and setting up the right muscles and alignment and is done consciously (at least at first). The second part of the shot is total focus on what you want to hit and the back end of the shot runs subconsciously. The only way to do that is to set is up before you begin aiming.
If you watch some of the faster shooters, like Terry, you will see the setup doesn't have to take a lot of time. But it has to be done the same way every time. And once you practice doing it the same way a few thousand times, it will become a subconscious process.
But the critical thing is to get the alignment, anchors and holding set up the same every time so that the result is a consistent follow through.
I hope I haven't confused any one, wish I was a better writer to explain this stuff.
Allen