I believe it was established in Star*Soldier that the events of Privateer took place in mid-to-late 2669, which would be concurrent with the events of WC3; it also established the events of Righteous Fire happening pretty much immediately afterwards. Not entirely sure that's consistent within the context of the games; you'd think they'd be talking about it in Righteous Fire if the Cats had been defeated. I suppose it's possible the end of the War didn't affect life in Gemini Sector all that much. Will entertain better suggestions there.
The date was probably established earlier than Star*Soldier too. I want to say the dateline is there in Privateer's introduction, but don't quote me on that.
- Wing Commander III itself doesn't have a great understanding of when Wing Commander III takes place. While the manual makes it clear that Blair is being transferred to the Victory around July 2669, the actual game doesn't say this anywhere... and the intention may have been to set it as many as seven years later! Some background: https://www.wcnews.com/news/2015/02/18/startling-discovery-adds-new-wc3-facts-to-the-universe (No later sources reference this and now totally contradict it... but it's interesting because that was apparently the choice made at a point when people *did* know when Privateer was set but nothing else that would later be established about 2669.)
- Righteous Fire is also problematic, as the intro begins "Jolson Pleasure Base. One year later..." implying that it's a year after a game established to have been set in 2669 (so... 2670.) The issue there is that the Kilrathi War is now established to have ended in 2669.