Thank you all. I have clipped the wire to barely accept the arrow shaft and it is centered on the button. There is room to move it forward or back a little though.
I asked this question because in my traditional recurve bow circles it is considered critical to have the arrow resting exactly at the pivot point of the bow which is above the deepest point of the grip. The shelf is carefully built up with a match stick under the shelf material to create this pivot point. The thought is to reduce torque.
Since getting interested in the FITA style bows I've found little things like this are major points of discussion. I'm glad to know I can quit worrying about this little detail and get on with shooting.
