I hadn't realized it until just now, but it was 50 years ago this month that I bought my first Marvel comic off the stands: Fantastic Four 9. I also bought my first Archie Adventure comics off the stands this month: Adventures of the Fly #23 and Adventures of the Jaguar #10 (another one of those dinosaur covers). I never realized until now that I first sampled Marvel and Archie Adventure in the same month.
The likely reason for this is that I had read a letter from Roy Thomas in JLA in which he touted the fanzine that he and Jerry Bails were doing together, Alter Ego. I started ordering fanzines from Bails and there first learned about super-heroes outside of DC.
Other comics I bought new fifty years ago this month (September):
Justice League of America 15
Showcase #41 (Tommy Tomorrow)
World's Finest 129