According to Comicbook.com,
During this time, the only superhumans we know to be active are Black
Panther (Wakandan monarch T'Chaka, played by Atandwa Kani), and
possibly Captain Marvel (a yet-to-be-introduced Brie Larson).
Her debut film, out in 2019, is set sometime during the 1990s —
decades after Captain America (Chris Evans), Ant-Man (Michael
Douglas), and Wasp (Michelle Pfeiffer) gave rise to the current crop
of Earth's mightiest heroes operating in modern day.
Of course, a brash and bratty Thor (Chris Hemsworth) is somewhere off
world, not yet the hero he would come to be in 2011's Thor.
The 1992 prologue sees a radicalized N'Jobu (Sterling K. Brown) come into conflict with his brother T'Chaka before Black Panther jumps to
one week after the events of Captain America: Civil War, which
introduced T'Challa (Chadwick Boseman) as a vengeful king-to-be
seeking justice for his murdered father.
That also puts Black Panther taking place before last summer's
Spider-Man: Homecoming. A title card early on in the movie has us
catching up with Peter Parker (Tom Holland) "two months later" after
his scuffle with the Avengers at a German airport.
Thor: Ragnarok, if you're wondering, takes place roughly around the
same time as Homecoming...
For your recommended eventual Marvel Studios chronological marathon,
you would follow Civil War with Black Panther, Homecoming, and then
Ragnarok, with the mid-credits scene of the latter heading directly
into Avengers: Infinity War.