When did Flash become The Flash?

When I was a kid I used to get D.C. comics for a dime (the occasional 80-Page Giants were a quarter). In those days one of the heroes was Flash. I just noticed a series on Netflix called The Flash. When did he acquire a definite article?

The first comic called The Flash came out in March 1959. So, at least since then. The original comic called just Flash Comics ran from 1940-1949.

Even in Flash Comics, Jay Garrick was known as The Flash. It’s right there on the cover of issue No. 1.

Well, then, perhaps I’m remembering wrong, or perhaps there was an era where it was just “Flash.” I bought comix mostly around 1965-1969.

EDIT: It would appear to be the former, here is a 1967 issue

Does anyone in the comic/ cartoon/ TV Show/ Movie ever call him The Flash?

Batman has gone back and forth being styled as both “Batman” and “The Batman”

And sometimes the title and the poster disagreed…

It usually depends if they’re talking to him or about him. In the recent show they’ll definitely call him “The Flash.” But if they’re talking to him it’s just “Flash.”

Close personal friends call him The.

Please, The is my father’s name.