When Does "Harbinger" #6 (1992) Take Place?
"Harbinger" #6 v1 "One For All" is a superhero comic-book written by Jim Shooter that released March 17th, 1992. So when is "Harbinger" #6 set?
It takes place on the fictional Valiant Universe timeline in the year:
We know this because during the story a character dies whose tombstone is visible in the next issue "Harbinger" #7 v1 (1992) and it reads "1972 - 1992" so it's currently within the 1992 AD calendar year.

1992 AD
We know this because during the story a character dies whose tombstone is visible in the next issue "Harbinger" #7 v1 (1992) and it reads "1972 - 1992" so it's currently within the 1992 AD calendar year.
Furthermore, the first textbox of page one contains time and place setting text: "The sub-basement of the Harbinger Foundation Research facility near Dallas, Texas, March 6, 1992, 12:41 A.M." so it's most likely March of 1992 AD.
This comic-book was retroactively collected into a "Harbinger" volume 1 subtitled "Children of the Eighth Day" and another subtitled "The Beginning".
It is an early chronological comic-book in the Valiant Universe (a chronologically eighth comic to feature the Harbinger characters) and can be read at its timeline point.