I've noticed that for a lot of the articles on this wiki there exists a sort of shared universe between the different characters by different users. A sort of "Witcher Fanon Universe" if you will.
Anyways, I've done a little bit of looking around, and I'm posting this timeline as a sort of rough draft for those who want to make their own characters. In particular, this timeline will focus a lot on the future of the Witcher world, after the events of the Witcher books and games, based upon what other creators have imagined.
230s BR: First Conjunction of the Spheres, which sees lots of monsters and magic appear on the Continent
1 R: The Resurrection 
760s AR: First Landing, with the Nordlings arriving on the Continent
950s AR: Creation of the first witchers
1181 AR: Destruction of Kaer Seren 
1249: Destruction of Kaer Seren 
1262-1263 AR: The First Northern/Nilfgaardian War
1267-1268 AR: The Second Northern/Nilfgaardian War
1271-1272 AR: The Third Northern/Nilfgaardian War 
1309-1318 AR: The War of the Two Unicorns in Kaedwen, possibly between rival houses fighting for the throne
1350 AR: The Haak Invasion, but eventually defeated
1358 AR: Second Conjunction of the Spheres, seeing lots of new monsters and threats, and the revival of witchers 
1530-1540 AR: The Colonial Wars in the colonies, only mentioned in Stefan's article
1730 - Stefan "the Crane" dies
 - For the starting point of the human calendar, there is literally nothing known about "the Resurrection" in the official canon. It's clearly inspired by the Christian death and resurrection of Jesus Christ, but otherwise there is annoyingly nothing else I know about it.
 - There is no known official date for the destruction of Kaer Seren. I read on this wiki that it was in 1249 (and there are other examples), and so that's what I used for my character. In Jorstadt's article it is much earlier, but that is the only example I can find of that has it differently.
 - This gets into some difficulty, because the games offer multiple endings, where either Radovid rules the north, Dijkstra rules, or Nilfgaard conquers everyone. I get the feeling that the general consensus is that Radovid one but his "empire" fell apart and things returned to a new status quo, but I'm sure different authors have different ideas about the future of it.
 - Putnam Pitch's article places this at 1380, but otherwise every other example of this places it occurring in 1358.
This is just a putting a bunch of author's own personal headcanon's and fanon's together, but hopefully this can serve as the basis for a generally accepted timeline of the future for anyone who needs it.
Anyone else have any information or ideas about the future of the Witcher Universe?