On the long list of things that Mr. Fallon nailed in his debut—the bit about people who bet him he'd never host and his emotional honesty about Johnny Carson chief among them—we'd like to add one more:
His tie bar. Short, but not too short (you never want one longer than the width of your tie). Fastened to the shirt placard (not just clipped on the tie!) between his third and fourth buttons. Classic silver.
Jimmy nails it. Just another reason to follow his lead on basically everything.