I guess you are shooting with the squaw hold (two handed).
If I determine that it is big enough and close enough, I will slip hammer. It may be nano seconds faster, but I am not locked into it. I am a believer of very light, no creep, triggers. If you teach yourself how to set off a light trigger subconsciously, it will be just as fast.
If you have smooth tuned handguns, the best thing to do is dryfire and teach your subconscious where the trigger is. By that I mean, teach the finger(mind) to put the first pad of the index finger on the trigger and just touch it after you come to full cock.
Then go the range, set up the pie plate on a big piece of cardboard and see if you can grip the revolver tight enough, hit the hammer just enough, and touch off the trigger without any of these motions influencing the barrel. 21 feet. 5 rounds in 5 seconds (at least)