The steroid use timeline isn't that complicated.
The first widespread use in sports is considered to have been by the Russian Olympic teams in the late 40s/early 50's.
The San Diego Chargers were giving it to their players in the early 60s.
It was widespread in football in the 70s.
Use in baseball was a little trickier. When I was in HS(late 70s), lifting weights was still a bit of a no-no for baseball players. The fear was adding bulk would affect your swing and your throwing motion. If a baseball coach caught you lifting heavy, you might be running laps for the rest of the season. Since most policy in HS filters down from college/pros, I'm sure the same theory applied at those levels. If you watch clips from that era, it's obvious that most of the players were allergic to the weight room. That began to change in the mid 80s. Players had lifting programs and, obviously, they got bigger/stronger. I think it was Dave Stewart, but the "baseball men" felt he was killing his career by falling in love with his muscles. Then, of course, Canseco came along and was wildly successful.
As for what people thought, I doubt there was much suspected steroid use in the late 80s/early90s. Men in their 20s/30s lift weights, especially professional athletes, they get bigger. That's just how it works. But, in the mid-90s, when guys who were 190 lbs were suddenly 230 and faster, or were suddenly having a career resurgence at 35, people began to think something was up.
I don't really believe anyone who says they felt steroid use was rampant in the late 80s/early 90s. Like it or not, I think Canseco is telling the truth when he claims he's responsible for widespread use. He was using and he had certainly had the personality that would tell anyone and everyone what he was doing.