Hi Wren:
My kids have been learning violin since they were 3.5, then we added piano when older was 9 and younger 7. I do not regret, but you have to know that this is a HUGE commitment on the parent site. Only now do I know that. Very difficult to pull through if both parents are working full time.
Only now, and they are in 7th and 5th grade , do they practice on their own (I still nag occasionally) because there are consequences of not practicing.
What I like about starting early is the fact, that by the time thya are in HS, both will be so advanced that quitting the instrument becomes a no option.
Violin is still the major instrument for both of them, with piano being a close second. I have a piano teacher coming to our house, so this was always a "very easy" solution for me, as there is no commute and wait time involved. They are both taking from the best (read very tough) teacher in the area. They are good. Saturdy both were graduating from their respective books (Suzuki) at the big concert and my sons group happened to be very small - only 4. As a 7th grader he was the youngest, visibly, the other three were HS. He was the only one playing with confidence (Bach concerto), even the teachers told him so after the performance, he kind of "saved the show" if you want. His teacher respons after the whole thing was over was "that spider in the second section was great, but there is still a lot to learn in that piece :-), and then she gave him a pat on his back. I love her
My kids have the heighest test scores in their classes, but is it because of music??? They know classical music and the elements of composition just by osmosis.
I don't even know if this answers your question?
If you would like some recommendation of books to read for you, as a parent, let me know.
Ania