The Day After He Left

"Maybe returning to New York on the day after he left it had been a mistake."
-Poul Anderson, The Shield Of Time (New York, 1991), PART ONE, 1987 A. D., p. 3.

This opening sentence (almost) immediately establishes that the viewpoint character has traveled through time. In an ordinary journey, you can return to your starting point on the following day only by spending a single night elsewhere. On the following page, we learn that Everard had:

"...enjoyed two easy weeks in Hiram's Tyre, taking care of leftover details after his mission was done. As for Bronwen, he'd provided for her..."
-op. cit., p. 4.

This passage not only confirms that he has time traveled but also reveals that The Shield Of Time is a direct sequel to "Ivory, And Apes, And Peacocks," which therefore should be the concluding story in the preceding volume, Time Patrol. (In my copy of The Shield..., the list of "Tor books by Poul Anderson" informs us that Tales of the Time Patrol is "forthcoming," so the order of the stories could have been rectified then.)

P. 3 gives us a description of a beautiful springtime in New York:

dusk;
air cleared by rain;
"...a ghost of blossoms and green..." drifting through open windows;
street lights and noises "...softened, turned riverlike."