Did the crowd energy for Reagan begin in August 1979? The most I remember is scenes from the GOP convention.
Reagan actually lost the Iowa caucus to George Bush and it appeared that he might be finished. But then he had the "I paid for this microphone" moment in NH and the tide started to turn.
However, as you point out, the magic moment for Reagan was the 1980 convention. Probably the greatest convention speech of the modern era. Even to this day, I watch it on YouTube from time to time. From that point on, Reagan was unstoppable.
Trump is way ahead of Reagan in this regard.