Any teaching involving the ear and memory will be fantastically valuable. Many potential fiddlers lose any opportunity to play well by being wrecked by staring at musical nptation too early. Sheet music is a fantastic way or writing down tunes for future reference, and a great source for leaning tunes quickly and easily, once you have learnt some style. But offered too early, sheet music is highly liable to destroy music in a person(tradiytional style music, anyway).
The best tune to learn is the one tour teacher/friend knows