I think I went to a my first, very small, Star Trek Convention in San Diego in 1986 or 1987. My memory on this is squishy. I know I was at age where I could drive. I know it was on Mission Bay — I think it was at the Bahia Resort next to Mission Bay.
http://artlung.com/blog/2020/04/03/star-trek-conventions/
http://artlung.com/blog/2020/04/03/star-trek-conventions/