I think you're getting pretty close to being ready to make a regular string. When I'm making a new bow, I tiller with a long string, (for me, I use the bow stringer I made), until I get the limbs moving about 8 or 10 inches . Then I switch to a shorter regular bow string. I put a loop on one end, and use a timber hitch on the other end, so I can adjust the string length while I finish tillering.
re: "Has Sam Harper been here?", I just got a pm back from him:
"I've lurked on primitivearcher.com, but I haven't signed up or participated in the discussions there."