On selfbows I keep it around 6 inches, or maybe just a tad higher. I would start around 6 1/4 and shoot it. Also give the string a chance to stretch in, about 30 shots should do it. Then lower it by a couple counter clockwise twists of the string and shoot it again. Keep doing that and listen to the bow, it will get smoother and quieter as it get's to the brace height it likes.