I use a Tru Fire X - Caliper release in relax to fire method. I draw my bow holding the trigger [the jaws are clamped on the string] as soon as I anchor and have acquired the target and sight pin, I slowly transfer to my middle finger [just the very tip of the triger]. Then all I have to do is start thinking of releasing and the shot goes off.

So yes my release is with my middle finger while the draw is accomplished with the index finger.

I hope this helps.