The ficitonal date?

In The Gambler Returns: The Luck of the Draw, 3 November 1991, there is apparently a fictional date of 1906.

/en.wikipedia.org/wiki/The_Gambler_(film_series)#The_Gambler_Returns:_The_Luck_of_the_Draw_.281991.29

Brady Hawks heads to San Francisco to play in a poker tournament in honor of "the late Mr. Paladin", thus putting it in the same fictional universe as Have Gun, Will Travel (1957-1963). If the last episode of Have Gun, Will Travel was 28 years before The Gambler Returns: The Luck of the Draw, the difference between their broadcast dates, it would have been in 1878.

Thus a rough estimate might be that Have Gun Will Travel should happen between 1872 and 1878.

Of course many episodes of Have Gun Will Travel may have evidence of their fictional dates or even explicit statements of the dates.

In The Gambler Returns: The Luck of the Draw Brady Hawkes also meets Bart Mavarick from Mavarick. The number of years since that show aired subtracted from 1906 could give its fictional date. the date of Mavarick is also indicated by some evidence in the episodes.

https://moviechat.org/tt0050037/Maverick/5c943dd3be89fc07f659a340/Some-Maverick-Chronology