I got out of the Navy in 1976, in San Francisco. A kid at the corner grocery kept going on about this fantastic new sci-fi movie coming out, and I just scoffed. Nothing could beat 2001. As May got closer, there was some "world preview" announced for a Thursday, so I took the bus out to the theater on Arguello and Geary (?), and wondered what all the lines were for. No one stands in line for science fiction movies! But they were for this. So I stood in line. Someone came down the line announcing this line was for ticket holders only, and I wondered what the heck was going on; no one buys tickets in advance for science fiction movies!
Then someone else came down the line, announced they had a few more tickets for sale, and I rocketed up, got my ticket, and was in the third row, looking up at the screen, scrunched down so I didn't have to bend my neck so much. Someone came out on stage, or maybe just on the floor in front of the screen, and gave a little speech about being the world premier. No idea who it was now.
And then the movie started, oh holy mackerel! That weird scrolling introduction "In a galaxy far far away" and then that huge spaceship, laser blasts all around it, theater rumbling, and then the REALLY HUGE spaceship came chasing it, firing all those laser blasts, theater felt like an earthquake compared to all my experiences with theaters, especially watching 16mm movies on the ship mess deck, holy holy mackerel!
And when it ended, nobody left. Well, I was third row, couldn't see the whole theater. And when the credits got to "modelers" everyone stood up and gave them a standing ovation.
Wikipedia says the world premiere was at a different theater and not on a Thursday. So I don't know what I saw. But I do know Hans shot first, screw Lucas.