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.
Is it just my, admittedly, faulty memory or did Reagan *own* that convention?
To me, it was the way he carried himself and his demeanor as much as what he said.
To me, it was so refreshing to have a man of courage and conviction confidently striding the stage.
Especially after the Watergate disaster, the ineptness of Ford and the nebbish that was Carter.
Watching the convention ensured my vote for Reagan.
I see some of the same in Trump.
The same confidence and grand vision.
But the devil is in the details.
Interest of others...VIDEO: Ronald Reagan Presidential Nomination Acceptance Speech - 7/17/1980
TEXT: Acceptance Speech at the 1980 Republican Convention, by Ronald Reagan (July 17,1980)