Mine...Pinocchio, which I can't figure out. I don't think it was rereleased in the 70's anytime, so it must have been one a Movie theater screened on its own. Still remember the whale scene pretty vividly and my mom using the be a good boy or you're going to grow a long nose trick on me.
Heh, that's back in the old days Scott, before there were VCRs, or have you forgotten that. The only way to see a movie was at a theatre. Or if the school brought in a movie. Like the LIttle Drummer Boy every year at Christmas?
Honestly I cannot remember that far back anymore as to what the first movie was

It might have been Sound of Music, possibly one of the Herbie movies or maybe Mary Poppins. I think it was either the first or last in that list, not sure why.
First movie I attended at a drive in was Live and Let Die, cool flick, but voodoo guys scared the crap out of me for years.
First movie I went to without family was Phantom of the Paradise. There was a cool theater only about a mile from our place and we went and saw it over and over again. Still enjoy it much more than Rocky Horror, mostly because of the memories.