Follow that!
Here are some standouts:
I saw Pink Floyd doing
Atom Heart Mother in Hyde Park, which was in July 1970, quite a while before the record was released.
One of my school mates drove three of us up to London (we lived in Hemel Hempstead) to see
Hawkwind at University College - this was before they were at all well known, maybe just before the release of
In Search of Space, or soon after.
In 1971 I saw
The Who twice, first in July 1971, about a month before Who's Next was released, but shortly after Won't Get Fooled Again came out, so it was the first time that I'd heard Baba O'Reilly, Bargain, Behind Blue Eyes; but one of my friends had bought Won't Get Fooled Again and I can remember them playing the B-side, Don't Know Myself. I saw them again at The Oval cricket ground in September the same year, which wasn't so good because the support bands were America (who I couldn't stand) and The Faces (who I could barely tolerate), and we had to leave while they were still playing Magic Bus in order to get the last train back to Hemel.
I stood next to the speakers right next to the stage (in Watford Town Hall) when I saw
The Groundhogs shortly after they had appeared on the Old Grey Whistle Test doing Garden and Eccentric Man from their album
Thank Christ For The Bomb (if you've never heard it, you're in for a treat), so this must have been 1970. My ears were still ringing the next day, and I still have tinnitus to prove it. I saw them again in 1994 at
a pub in Leeds when I did even more damage to my ears, and this is why I have noticeably different levels/tones of tinnitus in either ear.