My impression is to work the middle thrid of both limbs, the left a little harder. Looks like you are about to be able to string the bow, you are pulling it to 6" of bend and things look fairly smooth. Maybe short-string at a low brace (4") and quickly run a short straightedge along the belly to mark flat spots. You can get a lot of guidance fast using this approach, without doing much damage.
Somebody else ought to chime in, I don't have the best eye for tiller.