The link you’ve shared here talks about the Führer Oath being created in August 1934 but not becoming law until mid-1935, which seems to roughly agree with the date in the post you’re disputing. I can’t find much to support the claim about a surprise assembly, though, at least from a cursory search.

It looks as though his post is taken almost verbatim from this substack post: https://thecycle.substack.com/p/from-hitler-to-hegseth

which doesn’t inspire the most confidence.