Sounds about right for me, too. The band playing before Alice was a trio of unknowns. Two guys w/beards and a heck of a sound, by the name of ZZ Top. I hear later they made it big. : )
Ha, I was fortunate to see a couple of bands who later made it big as well. It was at Bucknell University around 1975 (we traveled over there from Penn State for concerts from time to time) and the headline act we went to see was Blue Oyster Cult. Opening the bill were a couple of unknown bands named Rush and Kiss.
I think I STILL have a headache from that concert.