Not before Dinah. I mean, in The Killing Joke she had a friend who was supposed to pick her up on their way to yoga class, but we all know how the rest of that night went...
And in the 80s origin story, she has a friend named Marcy from childhood, but I'm pretty sure that's been retconned out of there, and there's never any mention of it.
Before that, I guess it would've been pre-Crisis Supergirl, but that's gone too.