Youngest was 4, and came to a music club I used to run for infant school children through the music service. She could play a few notes on the recorder and had fun with singing and percussion.
Youngest private pupil was just 6, for piano but I prefer to start them later these days. Oldest was a 72 year old beginner on the clarinet. He passed his Grade 1 at 74 and came for lessons for about another year after that.
My own DD1 could read music and play all kinds of tunes using B,A,G on the recorder at 3.5. DD2 is 4 and nowhere near this. Of course, it fizzled out fairly quickly with DD1, but she took it up seriously at 5.5, and 15 months later is now working towards Grade 3 recorder, has done her piano Prep Test and reached Grade 1 level on the flute after six lessons
However, a career in sport is probably not beckoning!!
Wow, Cyrilla... I don't think anyone can beat that!!