When the picture in the scope is clear you should be ready to shoot. There are several ways to release a perfect shot. As long as it is smooth and done while aiming, it should work. To hit the trigger or let go of the string with a bang when you are in the center or just passing through it will not work, because that decision sends signals to all parts of your body that something is going to happen and the body will respond before you have a chance to execute a good shot. If you use a clicker, when the clicker goes try to execute the shot as smoothly as possible.
Some people squeeze or pull until the shot goes off almost accidentally.
What all these people have in common is that they all keep a slight pressure on the release trigger through the aiming process. Getting the release off is just a question of increasing the pressure as unconsciously as possible. Try to keep the dot still in the target or minimize the movement as much as you can during the whole process. Never mind where the dot is when the shot goes off, don't try to fix it. Just stand there like a mannequin trying to look like an archer that just shot a smooth shot.