Most guys heat the horn side ,and flex the limb to tiller . I try not to ,not sure why . I pre tiller both horn limbs ,before glueing together with the overlapping piece .Then I tiller the horn again as a complete horn only bow . So I figure the horn is right ,I don't want to remove any more horn after that . I think any tiller problems after starting sinewing ,have to be with my sinewing ....
After I get close to the weight I want , I may have to sand a little sinew or scape the horn a tad ,or heat and bend .(depending on unstrung ,strung ,and drawn profiles,, I try to keep them symmetrical ) But while I still have sinew to apply , I might as well apply it in a way that helps the tiller .(as log as the sinew doesn't get thicker in a spot than the same spot on the other limb) At least that's the way I look at it. I may be wrong .
Ralph