I've got some early 20th C. catalogues on my desk at the moment, so here
goes.
1902 Sears Roebuck + Co facsimile
Lists mining and forestry boots. Neither mention steel caps, and you'd
imagine them to be early adopters of anti-toe severing technology. Nearest
is the mining boot with 'a heavy iron toe plate'.
Boot section omitted in 1908 SRCo facsimile
1923 Anthony Horderns Catlogue [Sydney-based]
Small shoe section with work boots. None identified as steel capped or
similar.
These seem reasonably comprehesnive and the steel toe would be a specific
selling feature, so I'd expect 1923 to be a reliable terminus post quem.
cheers
Denis