When Does The Future Begin?

I thought of this question in relation to what I call the "Future History Triad":

Heinlein's Technic History;
Anderson's Psychotechnic History;
Anderson's Technic History -

- but, of course, every other future history that I have read came to mind so we wind up with a complicated list.

British
Stapledon's Last And First Men begins after "the European War";

Wells' The Shape Of Things To Come begins "today," in 1933;

CS Lewis' That Hideous Strength, not a future history but its author's reply to Stapledon and Wells, begins after World War II, with Jane Studdock remembering the words of the marriage service;

RC Churchill's A Short History Of The Future begins with a discussion of many well-known sf works on the fictional assumption that they are histories of the future;

Brian Aldiss' Galaxies Like Grains Of Sand begins with a future war and a commentary explaining that war in terms of instincts, fears and racial adolescence (Poul Anderson's "protean enemy" yet again).

OK. Maybe the Americans can have another post.