Flashbacks

The main action of SM Stirling's Conquistador (New York, 2004), Chapters One to Twenty Three and Epilogue, is set in the viewpoint character Tom Christiansen's "present," from June to December, 2009. The Prologue and Interludes are flashbacks to:

April, 1946
May, 1946
1950
1971
1962
1968
2001
1954
1997
1996
2003
2007

The Interlude following Chapter Eleven is the last as I have discovered by flicking ahead. I noticed that the second last Interlude, following Chapter Ten, is set in the author's present, the year of copyright of the novel. Thus, 1946-2003 is past, i.e., events on FirstSide are the same as in our history apart from the existence of the Rolfe family and of other fictitious characters, whereas 2003-2009 is future, i.e., events on Firstside may differ from those in our history although it is possible that Stirling avoids reference to such events in order to preclude any emergent discrepancies. In 2003, the Russians in New Virginia hope to learn how to create their own Gate or Gates, thus ending the Commonwealth monopoly.

Poul Anderson's Manson Everard, recruited by the Time Patrol in 1954, still lives in New York in 1990 and presumably knew of, e.g., Gorbachev as early as '54 although, of course, Anderson does not refer to that Russian Premier until The Shield Of Time, published in 1990.