How did they manage in the old days? They didn't have callers, people knew the dances.

Or, I imagine, if they didn't a caller would operate the same way they still do in a lot of dances today, by taking a few minutes teaching people how to do it before the band starts in to play the dance, and then more or less stands back, and perhaps shouts a bit of encouragement. Or stops calling and starts playing an instrument, or joins in the dance.