Found this today at NARA and fast tracked it for posting.

U. S. FLEET LETTER NO. 24L-38 (Revised) - Aircraft Tail Markings and Turret Markings for Aircraft Identification.

Released some time in 1938 and in effect until some time in 1940. The 1941 document Don Preul went public with mentions superseding a 1940 version, which is probably what superseded this one. I note that CruDiv 2's colors are different in this scheme than 1941.

It was part of a compilation of Fleet Letters then in effect... as such it did not have the original date of issue, but we can tell by the number that it was 1938 at least, and was in effect at least through October of 1939, when the compilation was dated.