First things first, hello FFG-forums!

I'll be to the point. We were having some thoughts in our group on exactly WHEN the official material of Rogue Trader is supposed to take place. Now, I might be wrong, but I'm pretty sure no official date is in the corebook, and I haven't read all the supplements. Is there an official date, or is it simply up to the specific GM to decide when (or roughly when) it all occurs? My guess was that 999.M41, but I really have no idea.

Thoughts?

 The official time line is 816.M41 (according to the Epoch Koronus web supplement, available on the Support page here listed as "A History of the Koronus Expanse"). It's free for an individual GM to shift as they see fit, though.

I believe the entire FFG line starts/takes place in 816m41/817m41.

 I've always struggled with the 40k time system. What does the time period really mean for the setting? Are there major events that haven't happened yet?

Well fluffwise:

"A Sisters of Battle fortress-convent, Sanctuary 101, is completely destroyed by Necrons. This raid is the first recorded contact with the Necrons."

and that was/ is going to be 897.M41

 The Second Tyrannic War (Hive Fleet Kraken) is due in 990.M41-993.M41, with the Third (Hive Fleet Leviathan) arriving in 997.M41. (the First Tyrannic War didn't really affect this area of the galaxy, but happened in 745.M41).

As has been said, first recognised contact with the Necrons happens with the Massacre at Sanctuary 101 in 897.

The Eastern Fringe is occupied with the Damocles Gulf Crusade against the Tau (been ongoing since 742.M41), and likely will be until Kraken or Leviathan.

In local news- the 13th Black Crusade is due at the end of the millennium, with an upswing of raids in the run-up.

The Badab War is due in 901.m41, as Chapter Master Lufgt Huron of the Astral Claws revolts and secedes from the Imperium. He is joined by three other chapters of Astartes.

941. M41, 2nd War for Armageddon. First major incident involving ork warlord Ghazgul Mag Uruk Thraka.

Basically, see here for a rundown of key events.

Tequila said:

I believe the current retcon is that Sanctuary 101 marks the first "official" contact with the Necrons, with earlier conflicts either leaving no survivors, being covered up by the Inquisition, or the information simply not becoming widespread for any number of reasons. This gives writers some leeway for using the Necrons before that date, as long as they don't become common knowledge. It's part of how FFG can use the Necrons in Black Crusade (the Imperium don't know that the Screaming Vortex is inhabitable) and Deathwatch (the Achilus Crusade is covered up to hide the existence of the Warp Gate between the Calixis Sector and the Jericho Reach).