Joe Bonamassa age 12
When B.B. King asks you to open for him you may consider yourself an accomplished musician. For Joe Bonamassa that happened when he was 12. By that point, he had a band and had been playing guitar for 8 years. He did have a couple of lessons in classical guitar from an instructor from Julliard, but generally, he just picked all the music by ear. 15 albums and numerous collaborations later he is still one of the greatest modern blues players.
His dad bought him a guitar at age 4 and played blues records for him.
Great video of him playing as opener for BB King in 1989 @ 12 years old