This technique was described in an unpublished, anonymous book on conjuring cataloged as “MSS III, 18” in the Biblioteca di Asti, Italy, dated c. 1670-1730. An English translation of much of this work was made by Lori Pieper in the Winter 2013 issue of Gibecière (Vol. 8 No. 1). In that translation, see pp. 106-109, where the technique is described and clearly illustrated. This remarkable entry also describes how the heel break may be collapsed to form a step, and it gives a method for forcing the cut at a card freely inserted by another person. This procedure seems remarkably close to one devised by Dai Vernon and published as “A Spectator Finds His Own Card” in Dai Vernon's Ultimate Secrets of Card Magic by Lewis Ganson, 1969, p. 135 (previously published in Harry Stanley's The Gen, Vol. 20 No. 6, Oct. 1964, p. 157.
The heel break laid dormant, at least in the published literature, until the twentieth century. Victor Farelli credited this idea to Glasgow magician Ernardo Veneri (c. 1847-48 - July 25, 1930) in Farelli's Card Magic, Part II, 1934, p. 65, titled “The Veneri 'Flesh' Break.” For more on Veneri, see Edwin Dawes in The Magic Circular, Vol. 101 No. 1092, July 2007, p. 208-210.