My understanding (Joe may confirm) that Dickey joined the band at 17. Probably the youngest guitar player to perform on the road.
Yes, Dickey left home at 16 and joined the circus to play in a band. After returning home, he and bassist Berry Oakley joined a group that became the Jacksonville, Florida-based group Second Coming. After a jam session in 1969 between Betts, Oakley and Duane Allman, and his younger brother Greg, the Allman Brothers Band was formed.
Following Duane's death in October, 1971, Betts took on more of a leadership role within the band and became its primary guitarist. He wrote songs like "Jessica," inspired by his daughter, and the group's biggest commercial hit "Ramblin' Man."