I tend to pay more attention to where the nock falls at full draw in relation to your eye as opposed to the string touching the nose, because today's shorter a-to-a brace heights can severely throw that relationship off.

Most people seem to agree that the nock should be in line (directly under) with your eye at full draw.

- let me add that I would certainly like my string to touch my nose as DaveC said, I just know that if that's all I go by, my draw length would change considerably between, say... my Tribute and my Constitution -- or at least my anchor would, and I'd prefer that stay constant.