In GARRET VAN HORN (1863), J.S. Sauzade refers to the use of "Sally Brown."

As the ship SPLENDID leaves New York, bound for China...

I began my sailor duty by heaving away at the windlass to the tune of " Sally Brown, the bright mulatter."

This sea voyage happens before the narrator become a soldier, in which he was shipped to the Kabyle War in Algeria, mid 1857. So Sauzade implies that "Sally Brown" was sung before then...but since it is fiction, we can only date the mention to the copyright date, 1862.