While waiting for my Pure to arrive, I'm going to build my arrows to past the time. This is a first time for me. I know what size/spine I want but am unsure how much longer do i cut the arrow compared to my draw length? Does it matter what rest i'm using? (octane pro) D/L is 31.5" so there's not gonna be much left on the end of the arrow blank anyways. Thanks for any help.