The date of 17 Aug 1934, however, is not the release date but the recording day. As written in the introduction of my list, "recording activity for Decca Records Inc. commenced in August 1934. The first blue-label American Decca records were released the following month priced at 35 cents for a 10-inch disc (55 cents for a 12-inch one). About one month later, Decca started its 7000 'race' series targeting the Afro-American blues and rhythm and blues market."
Actually I'm not sure about the release date of the first 7000s records but they definitely did not come before Sep 1934, rather in Oct 1934 (changed it to that month anyway).