Your first concert was to see who and when?

Elvis at the Chicago Stadium in 1976. I was 10. 

First ever concert was Queen in Frankfurt 1978. 

Arlo Guthrie - my parents took me and my brothers to see him in ~1975 when I was 8. My parents were scandalized that a couple sitting one row in front of us were snorting white powder off a small mirror. Took years for me to realize they were doing coke.

The first concert I went to deliberately was Tom Petty and The Heartbreakers with Bob Dylan in 1984 at Madison Square Garden. Dylan’s career was at a nadir and Petty went on tour with him to support Dylan by introducing his fans to Dylan’s work. Dylan didn’t do himself any favors because he was awful live.

Air Supply, 1980 at Luther College (not the hall Dave Matthews recorded at).  10 years old.

I can't remember the order, but I saw both Jethro Tull and King Crimson, late 1970/early 1971, Colston Hall, Bristol. Both were amazing.