In slogging through searches of the millions of titles on Google Books and Hathitrust Digital Library, the AN470 Universal Head seems to have became standardized in the late 1940s or early 1950s.
Aero mechanic's questionnaire. Los Angeles, Aero Publishers, 1955: Says "This rivet was developed after the war and generally replaces round-head, brazier head, modified brazier-head, etc. rivets for uses where protruding head rivets are needed. Original rivets of the kind mentioned can be replaced with the AN 470." Another early mention of AN470 is 1950 in Western Machinery and Steel World where AN470 is mentioned as "recently standardized". The Magazine of Standards, Volumes 24-25, 1953 mentions standardizing on universal head to save money. The universal head is briefly mentioned in Aluminum and magnesium design and fabrication, 1949.
The AN470 or "universal head' rivet is not mentioned in the list of rivet types in either the 1945 U.S. Navy training manual Aircraft metal work, Prepared by Standards and Curriculum Division, Training, Bureau of Naval Personnel, Washington, U.S. Govt. Print. Off., 1945 and not mentioned in the 1951 U.S.Navy Aircraft structural maintenance, prepared by Naval Air Technical Training Command for publication by the Bureau of Naval Personnel, 1951. The unversal head rivet is finally listed in the U.S.Navy Aviation structural mechanic 3 & 2, Navy Training Courses, 1956 for use "when existing stocks are depleted."
Aircraft manuals which list the aircraft's rivet types are hard to find, but occasionally a list of rivets will be given in repair or structural manuals on ww2aircraft.net or avialogs.com. The T-6 Structural Repair Manual, 1943 lists rivet types but does not include AN470 or universal head rivets. The AN 01-60-3 Structural Repair Instructions for A-36 Series and P-51 series, 1943 (revised 1945) does not include any information on AN470 or universal head rivets.
Earliest mention of AN470 I found in NACA reports was 1952.