When was the first mention of 2053 as the end of the Third World War within the Star Trek franchise?

Question

In any medium whatsoever — novels, interviews, movies, television episodes, etc. — what is the first mention of 2053 as the end of the Third World War?

Answer 1

For TV/movie references see the Memory Alpha entry for 2053 -- in the movie Star Trek: First Contact (1996) they travel back to 2063 and before they find out the exact date Data estimates they have arrived "approximately ten years after the Third World War", then in the Enterprise episode "Terra Prime" (2005), Tucker says "We didn't make contact with the Vulcans until ten years after the war", which would pin the date more precisely to 2053 (though I suppose it could be 2052 if it was 10 years and a little over 3 months or more, since the movie gave the date of contact with the Vulcans as April 5, 2063).

For written works, the earliest published reference given on the 2053 entry on Memory Beta is a book called The Sundered (2003), which according to this google books preview page pegs the date as 1 May 2053 for the date of the nuclear exchange, which seems to be what characters like Data and Tucker mean when they talk about a certain number of years "after the war".

The novelization of Star Trek: First Contact by J.M. Dillard (1996) also had a few references to the war happening 10 years earlier, though again not specific enough to say whether it was 2053 or 2052. Anyone with a scribd membership can read it here, for example here's a line from Lily's internal monologue on p. 41:

It was hard, after ten years—a whole third of her existence—to remember much about life before the war.

Or on p. 231, when Zefram first takes the Phoenix to warp speed:

Zefram Cochrane let go a scream—of fear, of exhilaration, of the purest joy—and with it, released ten years’ worth of grief and cynicism, pain and hopelessness.