I'm also not sure what you're asking, but will give my detailed opinion as to how to determine your trigger operation. A bonus is that this can be done at home.
Let's see what kind of discussion this will bring:
The numbers below are so I can refer back and forth, but as you complete each numbered step, you might want to take a short break before moving on. If you do take a break, perform a few dry fire operations of the previous step before you move into the new one.
(1) First, make sure whatever gun you're working with is totally unloaded and there is no ammunition around. Set it up for dry fire training. Also ensure you're in a safe area to point the gun around ("all guns are always loaded") and bring a chair to the area. Sit in the chair and position yourself comfortably with the gun pointed in a safe direction. Check again that it is unloaded and ready to dry fire. While keeping it pointed in a safe direction, dry fire it several times without looking at the gun. Do look into the direction it's pointed, to remain safe. Get the feel of what it takes to fire the gun. Reset and dry fire it this way until you reach a consistent feel. Vary the timing somewhat and look for a comfortable trigger operation that proceeds from start to finish in one continuous uninterrupted motion. Then settle on a time for completion based on how it feels. Practice that operation and study all the details you can think of about it. Especially note how long it takes to complete. Make the operation consistent.
(2) Now, still seated, start watching the gun as you perform the identical trigger operation. Look at it from above the sights instead of through the sights. Check how steady it is. If it sways as you operate the trigger, try changing the trigger finger placement a bit to settle it, but keep the same trigger operation as before. Again, study the feel and the timing and try to make this operation identical to (1) above. Move back and forth between (1) and (2) until they match.
Note: It is very common to slow the trigger process as you start looking at the gun due to judgment of what is happening. Suppress this impulse. Too slow a trigger operation will allow you to cover up any misapplication of the trigger, and is often the result of a start/stop movement, rather than a continuous operation.
(3) Once you've matched the feel and timing between the two above steps, you can move to sight alignment. Note that sight alignment means aligning them with each other as viewed from your shooting eye. It does not involve a distant aiming point; just the sights and your eye. While still seated and while still pointing the gun in a safe direction, extend your arm such that you can see the sights in alignment. For this, you can rest your arm against the chair or your leg, but do this comfortably and have the rest point well above your wrist. Now perform the same trigger operation as you came up with for (1) and (2) above while observing the sights.
Note: Observation of the sights means simply observing what they do when you operate the trigger. Don't allow your observation to direct your trigger. If your sights don't stay aligned, work with your grip and trigger finger placement to minimize the sway. Keep the same trigger operation as in (1) and (2) above.
(4) After you match the feel and timing for all three above, move to working with your normal stance, still without the distraction of an aiming point. Perform the same operation as in (3), and again, work toward an identical trigger operation as you had back in (1) and throughout.
(5) Now you can add the aiming point. This will be the most difficult time to try to get the same trigger because you will start judging the hold. Resist the impulse to wait for perfection to operate the trigger. Learn how to operate it the same as in the steps above with the same feel and timing and let your subconscious take care of your hold and coordination of the shot break. Once you're comfortable with the above, you can head to the range and do some live firing.
Additional thoughts (opinion): If you train with the above method and can learn a consistent trigger operation, that your subconscious can rely on to alway take the same length of time to complete, your subconscious can take care of all the details of making the shot hit center, including when to start the trigger. As soon as you vary the operation of the trigger, your subconscious has invalid data for its calculations.
Flame suit ready - pour it on guys...
Take Care,
Ed Hall
http://www.airforceshooting.org/
http://www.starreloaders.com/edhall/
http://www.geocities.com/ed_ka2fwj/