What is Earliest Musical Usage of "Jazz"?

[Jewls2u]

I do research for novelists, including myself, and this is what I came up
with regarding Jazz/Jass:

The legend goes like this: the word "Jass" was some vague slang for sex, and
was associated with prostitution. Tom Brown's band had come North from New
Orleans in 1915 and was playing a successful engagement at Lamb's Cafe
(located at Clark and Randolph Streets) against the wishes of the Chicago
musician's union. The term "Jass" was used by the union as a way to
denigrate the band. In defiance of the union Brown and the club owner
started advertising the band as Brown's Band From Dixieland . The union's
insults backfired increasing the popularity of the group and causing the
term "Jass" to forever be used to describe the New Orleans style of
collective improvisation.

http://www.redhotjazz.com/brown.html


Roots of "JAZZ"
A little bit of Etymology.

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JAS, JASS, JAZ JASCZ, or just plain JAZZ
It is said that the expression -'Jazz'- arose during the late nineteenth
century in the better brothels of New Orleans, which provided music and
dancing as well as sex. The original jazz band, according to Herbert
Asbury's 'The Latin Quarter'* (1938), was the 'Spasm (sic) Band', made up of
seven boys, aged twelve to fifteen, who first appeared in New Orleans about
1895. They advertised themselves as the "Razzy Dazzy Spasm Band." When,
about 1900, another band adopted the same billing for an appearance at the
Haymarket dance hall, the 'Spasms' loaded their pockets with rocks and
dropped by to protest the infringement. This prompted the owner of the hall
to repaint his advertising placards to read: "Razzy Dazzy Jazzy Band!" If
the memories of Asbury's sources were correct--and he talked to two
surviving members of the 'Spasms' --this represents the word's
earliest-known appearance in print.
Jazz is not a bad word now, but almost certainly is of extremely low origin,
referring to copulation before it was applied to music, dancing, and
nonsense (i.e., "all that jazz"). "If the truth were known about the origin
of 'Jazz' it would never be mentioned in polite society . . .The vulgar word
'Jazz' was in general currency in dance halls thirty years or more ago"
(Clay Smith, "Etude," 9/24). "According to Raven I. McDavid, Sr., of
Greenville, S.C., the announcement, in 1919, of the first 'Jazz band' to
play in Columbia, where he was then serving in the state legislature,
inspired feelings of terror among the local Baptists such as what might have
been aroused by a personal appearance of Yahweh. Until that time 'jazz' had
never been heard in the Palmetto States except as a verb meaning to
copulate" (H. L. Mencken, 'The American Language,' Raven I. McDavid, Jr.,
1963). "'She never stepped out of line once in all the years we been teamed
up. I can't sell her on jazzing the chump now'" (William Lindsay Gresham,
'Nightmare Alley,' 1946).

http://nfo.net/usa/etymol.html

  *This is actually from Herbert Asbury's book The French Quarter, 1936, pgs
437-8.

I didn't look to verify any of the other cites because they are not
referring to musical usage of jazz and are dated after 1915.>

Julienne