i would say if you start to tiller the bow,, and the weight does not go up,, it is pretty dry,, you can always stop if you think it is not dry enough ,, and continue at a later time,, it is pretty forgiving,,, I do have a feeling,, that the best performance may come from properly cured sinew,, but have no proof of this,, the bows I started to early,, did gain weight,, but seemed to perform well despite the early start,, a wider design my have the same amount of of sinew as a narrow thick design, but dry quicker cause the sinew is not so thick,,there are lots of variables ,, and we are still re learning many things that have been long forgotten,,,I love sinew backed bows