It is spurious to assume that the French Revolution somehow originated the term, or otherwise set the standard for what could be called a "revolution". The reality is that different revolutionaries in different periods of history perceived the term differently. The Glorious Revolution of 1688 would be a much more immediate example to 18th century Americans.
Consequently, the American Revolution was called a Revolution from the onset, at least by some of its participants.
As early as 1776, William Henry Drayton drew explicit comparisons to the earlier English (British) Revolution in his charge to the South Carolinian grand jury.
Carolinians: heretofore you were bound - by the American Revolution you are now free. The change is most important - most honorable - most beneficial ... Unexpected, wonderful and rapid Movements, character the British and American Revolutions: They do not appear to have been premeditated by Man.
- A Charge to the Grand Jury, April 1776
Similarly, the great Thomas Paine made no uncertain references to the revolt as a "revolution". In 1778 he famously praised the American Revolution to be the most "virtuous and illustrious" ever.
But this distinguished era is blotted by no one misanthropical vice. In short, if the principle on which the cause is founded, the universal blessings that are to arise from it, the difficulties that accompanied it, the wisdom with which it has been debated, the fortitude by which it has been supported, the strength of the power which we had to oppose, and the condition in which we undertook it, be all taken in one view, we may justly style it the most virtuous and illustrious revolution that ever graced the history of mankind.
- The American Crisis No. V, 21 March 1778
By 1779, Congress itself ordered the publication of something titled Observations on the American Revolution. Although some contemporaries seemed to have conceived of the conflict more as a British civil war, by the time it was over, it had become "the Revolution" (displacing the previous Glorious Revolution), at least to the Americans.
It is well known that they have heretofore had serious and animated discussion concerning the rights to the lands which were ungranted at the time of the Revolution, and which usually went under the name of crown lands.
- Federalist No. 8, 20 November 1787