Fred Braue was the pioneer in using a concealed sidejog to delay the control of one or more cards. See More Card Manipulations, No. 1, 1938, p. 47.

This predates Marlo's claims in Control Systems, 1952, p. 87. Also note Marlo's Delayed Fan Control, ibid., p. 83, in which three steps are used to preserve the locations of three cards while fanning the deck. This predates the recording of this technique used for just one card in Vernon's Ultimate Secrets of Card Magic, 1969, Pressure Fan, p. 128. Marlo didn't record this control method for just a single card, which is an odd lapse for him, and the idea of developing a three-card step control without having seen its one-card possibilities seems most unlikely. It leads one to wonder if Marlo wasn't building on an existing unpublished idea (Vernon's?), but failed to mention it. Only speculation seems possible on this matter.