Interesting thread-
Over the summer our 4 yo received the gift of a violin lesson with a fiddle/violin teacher. His favorite sitter thought of it for him
He has been begging since August to start violin lessons, and I just had the phonecall with the teacher who now has a 3 mo baby. We are starting a lesson once a month with a rented violin, with the understanding that he is to practice 4-6 times a week. She said that even if it's 15 mins a day, but NOT to practice if he's unhappy as it's counterproductive.
I'm actually a dabbler, so I'll be interested to see if this is a lasting passion, or just an exploratory interlude. Either way it's fine with me. Nick insists he wants to practice everyday with his own music stand and book.

He's already getting plenty of exposure to music- we've got a piano, drum kit, trumpet, and percussion stuff in the house. He refused piano lessons- because it's "boring" to him- he says he's fascinated by strings and valves. No trumpet teacher here for 4 yos, so violin it is...
Interesting to read your experiences, folks!