Today I have been reviewing the archives of my ancient advisor, LJ Boya, who is long absent due to health issues, and of course there are some folders on octonions.
An early attempt to use “octonion calculus” is as early as Pais 1961, but it seems that they became a source of inspiration for model building later the seventies, particularly http://inspirehep.net/record/100124?ln=en “A Universal Gauge Theory Model Based on E6” by Gursey, Ramond and Sikivie.
After this, in the eighties, we have the rediscovery that Susy and Division Algebras had a common source. Kugo-Townsend 83, Gunaydin-Sierra-Townsend 83, Evans, and later Sierra 87, Foot-Joshi 87 and Evans 88. And of course Adams in his Lectures on Exceptional Lie Groups.
Surely it can be argued that most of the work is really about Jordan Algebras and so all of them come really from Jordan-Neumann-Wigner 1934