bauhaus in 1925 has been linked in a peer comment.

i've got a 1926 print book is 5 by e e cummings who famously often used lowercase in his prose and poems ... going back earlier than the collection i have.

* https://en.wikipedia.org/wiki/Is_5

* my sweet old etcetera - https://web.archive.org/web/19991008163420/http://www.geocit...

still, as you're a fan of that 1960's show ... here's a few samples: https://www.youtube.com/watch?v=9dm_iq5OicM (1985)