"Lucy Long" as a song appeared in 1842, authorship claimed by Billy Whitlock of the Virginia minstrels.
Later, Daniel Emmett wrote Lucy Long sketches and songs, one of them mentioning attendance at a camp meeting. I have a suspicion that Emmett, with Jenny Lind, wrote the 1854 version, using 'Lucy Long' as a pseudonym. A suspicion, no proof.

John G. McCurry edited the Social Harp. The Sacred Harp website (http://fasola.org/maps/social.html) gives 1855 as date of first publication. Social Harp
A review of the University of Georgia reprint in the "Yearbook of the International Folk Music Council" also gives the date as 1855. In other words, the minstrel song, the Know Nothing songs, and the Social Harp version (posted above from Lomax (Pullen) all came out about the same time.
I believe the minstrel song was first, but no firm evidence. The version in the Social Harp is similar to the that of the sheet music by Holland, 1854. I can't find any evidence of earlier publication. (Rounder issued a cd of Social Harp songs, including "Few Days.")

The Albert Holland song, published in 1854 by Miller & Beacham in Baltimore, has a cover which says "as sung with great applause by Christy's Minstrels, music arranged by Albert Holland," so it is another of the Christy Minstrel versions. As I posted in Oct 29 05, it seems to be the one which was revised for the Social Harp.