DC, I think my last post should answer your last question. If not, let me know.
By the way, you need a line drawn to indicate perfect nock travel as the bow is drawn... not a line drawn parallel with the shaft sticking out in front of the handle. It's good that it helped enlighten you, but what are you going to do when the bow is drawn farther and there's not enough arrow out front to get a good read on it?
The bow's limbs can be balanced in strength with no arrow on the string by adjusting their strength so the nock point comes down a line drawn on the wall behind the tree to indicate perfect nock travel. If I was home I'd post a picture, but I'm at work on my phone.