The earliest example so far noted of an All-Backs effect done with just a few cards is “Junior's Card Trick” by Edward Marlo, published in The Cardician, 1950, p. 190. Marlo's routine appears to use four cards, which transform to have backs on both sides, then faces front and back. At the finish, the cards are shown to be normal and unprepared.
A popular variant of this idea appeared in the early 1970s: “Hofzinser All-Backed”, by Harry Riser (miscredited to John Thompson), published in Epilogue, No. 12, Jul. 1971, p. 91. The Riser routine, done (apparently) with three cards, combines J. N. Hofzinser's “Everywhere and Nowhere” plot with the All-Backs effect. Tricks by Al Saal and Milton Kort were later identified as inspirational to Riser's trick; see Saal's “Three Card Trick” and Kort's “All Backs Finish” in Epilogue, No. 13, Nov. 1971, p. 99 and 100.