Ran a search and noticed a few seemed to be assuming WFRP was set squarely before the Storm of Chaos, but a quick glance at the core rulebook offers the following:

...rumours of a champion of Chaos called Surtha Lenk and his great Chaos host waging war against the armies of Kislev. Information seems suspect and unreliable. Some of the news reaching Reiklanders speculates that Wolfenberg was sacked. Conflicting rumors insist Surtha Lenk's army was defeated, while others hint that the forces of Chaos were but the vanguard of a massive army poised to overrun Kislev and invade the Empire.

The Surtha Lenk SoC stuff occurs in 2521, as the whole thing is getting into full swing (it wraps in 2522, right?).

This is all only of concern to narrative canon purists, so admitting that I am one (or aspiring to be) what's your sense of where things ultimately stand with WFRP core here? Pre-SoC, or really more "contemporaneous with"?

I believe that the whole theme was "Cometh in the sky". So the "doom" was "awerted" with the defeat of Suthar Lenk and the Empire draws a breath.Only to realise the true war just beginning.

For timeline, check KalevalaHammer and Hapimeses forum.

everything points to a 2521 start date however i think they have the ability to alter things which i suggest they do...

Go on fantasy flight destroy peoples knowledge and building something knew it will be more fun this way...