Thursdays normally, 21:00GMT, but maybe that needs to be changed. At least for the past 3-4 months it's been deserted and before that it was really only Herr B. and me.
And what you do or don't in there, no one really cares. There's a target range with trucks waiting to be toasted, a "light" objective and a more involved one. I plan to add more light ones, since they can be completed by a single aircraft.
Suppose I'll update
this one soon with the new mission, and post notes about server coming up, Thursday or not. Generally will be between 21:00-22:00GMT.