No matter which end you twist or untwist, the twists will quickly equalize between the top and bottom when you string the bow, so the nock point won't change much, if any. Once you put on a few string nocks, you'll get quick enough at it that you can cut one off and replace it in a few minutes. I use nocks both above and below the arrow, and often find that I'm not happy with the spacing or location of one or the other after I put a new one on and cinch it down. I just cut it off and replace it. That's why I don't put glue on them: because I know they will eventually have to be replaced, and the little extra life I get out of gluing the knot isn't worth the extra hassle of cutting off a glued on nock.