RFC 4949 (Internet Security Glossary, Version 2) from 2007: https://datatracker.ietf.org/doc/html/rfc4949
$ end-to-end encryption
(I) Continuous protection of data that flows between two points in
a network, effected by encrypting data when it leaves its source,
keeping it encrypted while it passes through any intermediate
computers (such as routers), and decrypting it only when it
arrives at the intended final destination. (See: wiretapping.
Compare: link encryption.)
Examples: A few are BLACKER, CANEWARE, IPLI, IPsec, PLI, SDNS,
SILS, SSH, SSL, TLS.
Tutorial: When two points are separated by multiple communication
links that are connected by one or more intermediate relays, end-
to-end encryption enables the source and destination systems to
protect their communications without depending on the intermediate
systems to provide the protection.
There's a bunch of older references as well. Since SSL/TLS wasn't really adopted by a lot of services until 2008+ usages of it are mainly in papers, old forum posts, etc. I saw it used and was discussing it back in the day on IRC with folks who were way more knowledgeable than me on this topic and had been in the trenches for a while :D
I addressed the other two at https://news.ycombinator.com/item?id=46132220 .
You did show that the term was already used, but in the current meaning
That paper is about PKI-based session setup for End-End which is the ancestor of SSL/TLS. It even mentions a CAE which is effectively a CA and it does a synchronous handshake to establish a symmetric key. It's very clearly about transport layer security from end to end.
It's not about User-User E2EE (akin to Signal) and shares very little other than that data is encrypted from point A to point B.