The transition date for TCP was Jan 1, 1983 (see RFC 801 and various other documents by Crocker, et al). I don't recall any shutdowns, though my Arpanet access at the time was limited to a dial-up TIP and some PDP-10s at MIT, and I might not have noticed. There wasn't any kind of summer holiday shutdown at the university I was at, nor at NBS (where I was interning).
The grad-level computer networking course I was taking in early '82 mentioned ISO (we used Tannenbaum, recently published, as a base text). The professor pretty much threw his hands up at all the ISO layers. "This is not how you implement networking in real life."
There's a lot to like in IPV6, as well as some things to hate. Transitions remain difficult, but seem unavoidable (sooo much software smuggles IP addresses in 32-bit ints, and changing millions of lines of code and updating database schemas to match is not very much fun).
Your right that ISO's charging an arm and a leg for the printed docs was a mistake.
And the big switch only worked because it was done during the summer holidays and you could shut down things whilst it was done.
OSI would have not had the Omnishambles that is ipv6