Origins of the term 'WYSIWYG?

[Tony Duell]

Does anyone have any thoughts as to when that term, or a near
equivalent was first
used?

The reason I ask is that I have been looking in some old photographic books and
have turned up a 1954 advert for the Wrayflex (an obscure British single lens
reflex camera). The text ends with :
;...through the lens focusing at any distance. No adjustment for paralax. No
coupled rangefinder. Just the simple axiom ...
"What you see, you get" '

I wonder what predates that usage (if anything)

-tony