The page was written using Adobe PageMill 3.0, which was released in 1998 and discontinued in 2000 (https://winworldpc.com/product/pagemill/30), and references a Michael Quinion "Wierd Words" page created September 2, 2000 (https://web.archive.org/web/20031202154745/www.quinion.com/w...) which might narrow down the range a bit further.

GWS suggest February, 2001, as I see it:

https://www.google.com/search?q="How+SHRDLU+got+its+name"&hl...

I've done worse: https://news.ycombinator.com/item?id=23203180