The first time I heard the term in graduate school was actually applied to historians of the North Pole who claimed Robert E. Peary did not reach the Pole. But I think probably the first “authenticated” revisionist in America was Charles Beard with his “Economic Interpretation of the Constitution.”
This was published, I believe, in 1913, and may have been the first revisionism of the Progressive movement, but it is not the first revisionism in America.
An earlier example would be referring to the 1860's failed war of independence as a "civil war". It was no more a civil war than was the successful 1776 war of independence. History is written by the victors.
I expect that someone could come up with an even earlier example.