When Does "Professor Marston and the Wonder Women" (2017) Take Place?
"Professor Marston and the Wonder Women" is a historical fiction film written by Angela Robinson that released October 13th, 2017. So when is "Professor Marston and the Wonder Women" set?
It takes place in the years:
We know this because it opens depicting the real-world Olive Byrne first meeting the real-world comic-book writer and psychologist William Moulton Marston and his wife psychologist Elizabeth Holloway Marston, which happened in the real world at Tufts University in 1925 AD. The main action begins just before a title card over the footage reading "Harvard Radcliffe College, 1928". This can be seen as a production mistake but it's always possible that 1928 AD is when (and Radcliffe where) they first meet within the story's fictional world (diegesis).

1925 AD - 1946 AD (or 1947 AD)
We know this because it opens depicting the real-world Olive Byrne first meeting the real-world comic-book writer and psychologist William Moulton Marston and his wife psychologist Elizabeth Holloway Marston, which happened in the real world at Tufts University in 1925 AD. The main action begins just before a title card over the footage reading "Harvard Radcliffe College, 1928". This can be seen as a production mistake but it's always possible that 1928 AD is when (and Radcliffe where) they first meet within the story's fictional world (diegesis).
A little more than halfway through the narrative, a title card appears reading "Greenwich Village, NYC, 1940" so presumably it's 1940 AD. This does not seem to be confirmable by context.
Later, the audience sees the conception, development, and initial publication of the fictional character Wonder Woman. In the real world, Wonder Woman first appeared in the pages of "All-Star Comics" #8 (1941), which released on October 21st, 1941 AD. The first script Marston drops on the desk of the real-world comic-book publisher Max Gaines (though he is attached to National Periodical Publications when he was, in fact, co-publisher of All-American Publications-- both precursors to DC Comics), is dated for "November 23, 1941" in the movie. This happened in the real word in February of 1941 AD. So at least this portion absolutely takes place in 1941 AD.
Additionally, there is a frame story that opens the film clearly labeled right away with its own title card as presenting us "National Comics Publications, New York, 1945" and depicting a meeting between Marston and the real-world then-"Director - Child Study Association of America" "Josette Frank" (as described by a title card). So it is presumably 1945 AD during these framing scenes.
The frame story resolves and leads into the final part of the work. Just before this happens a 1946 Chrysler DeSoto is visible in the background; yet this final part is clearly before William Moulton Marston's death on May 2nd, 1947 AD. So it is either 1946 AD or early 1947 AD.
There's also a prologue depicting a comic-book burning, something only done with any regularity in 1955 AD.