the UCLA Chicano Studies Research Center,
the Arhoolie Foundation,
and the UCLA Digital Library
78 was sent for processing of 2000 copies on July 16, 1947. Recorded test pressing. First reference to word Chicano.
I believe this is not the first reference to word Chicano as your collection contains "Amores Chicanos" by Noloasca &Ramirez which was recorded in early 1926.