When Does the Third Film "The Age of Innocence" (1993) Take Place?
"The Age of Innocence" is a historical fiction romance film written by Jay Cocks with Martin Scorsese [adapting "The Age of Innocence" (1920) by Edith Wharton] that released September 17th, 1993. So when is "The Age of Innocence" set?
It takes place in the year:
We know this because the very first scene depicts a performance of the opera "Faust" (1859). Since Faust was first performed on March 19th, 1859 AD in the real world, it must be after March of 1859 AD. A mention is made of "trunks of dresses from Worth" in Paris. The real-world fashion designer House of Worth closed in 1956 AD. So it must be before 1956 AD.

1874 AD - 1878 AD
We know this because the very first scene depicts a performance of the opera "Faust" (1859). Since Faust was first performed on March 19th, 1859 AD in the real world, it must be after March of 1859 AD. A mention is made of "trunks of dresses from Worth" in Paris. The real-world fashion designer House of Worth closed in 1956 AD. So it must be before 1956 AD.
Furthermore, at one point May Welland says, "And the Merrys are setting up the lawn tennis court. But nobody here has really heard of the game so..." The real-world game of tennis was introduced to the United States of America in 1874 AD. It seems that it must be just during or after 1874 AD.
12.1875 + 6.1 = 1877.
More specifically, almost halfway through the movie, the characters attend a performance of "The Shaughraun" (1874), a stageplay first performed on November 14th, 1874 AD in the real world. So it must be after November of 1874 AD. Based on the line "It's fascinating. Every season the same play, the same scene, the same effect on the audience." from Larry Lefferts, it's almost certainly been at least 1 year, so now it's during or after November of 1875 AD.
"He had heard her name often enough during the year and a half since they'd last met." is heard from the narrator, referring to Newland Archer and Countess Ellen Olenska, telling us we have certainly moved not just into the next calendar year but the one after that: After her return from her honeymoon in Europe, May is shown taking part in an archery competition and a banner in the background reads, "NEWPORT ARCHERY CLUB AUGUST". So it is certainly August of 1877 AD.
12.1875 + 6.1 = 1877.
Later, Newland says to Ellen, "Have you seen this? The new stylographic pen." The first stylographic pen was patented in the United States of America in 1876 AD confirming it must be past that point during this part of the story.
Soon after that, the secretary named Rivière says to Newland, "My name is Rivière. I dined with you in Paris, last year." That was during the honeymoon, so we've moved again- now to the 1878 AD calendar year. This is probably where the main action ends.
1877 + 1 = 1878.
Furthermore, the very first shot includes a time and place setting title card reading: "New York City, 1870’s". Though this is quite vague the context clues get us specific years.
Additionally, there is an extended epilogue that jumps far ahead and is mostly unplaceable. Theodore 'Ted' Archer says, "I'll have to sail next Wednesday on the Mauretania." The real-world ocean liner RMS Mauretania first sailed on November 16th, 1907 AD and was decommissioned in September of 1934 AD. So it must be after November of 1907 AD but before September of 1934 AD during the epilogue.
More specifically, at this time, Ted says, he has to get "the score of the last Debussy songs". The real-world musician Claude Debussy died in 1918 AD and his last music was produced in 1917 AD. He might just mean the most recent music but this seems an unusual choice of words verses the simpler: "newest". The lack of mentions of World War I while the characters are in Europe where the worst of the fighting happened, makes it most likely to be 1919 AD or soon after.