[Russell Sobie]

I think it's literally after the first race in a series. So if you get 1st place in the first race of a series, and then register for the second race later that day... you'll likely be on Server 1 no matter what your driver rating is. Mr. SRS Admin likes to keep his various algorithms close to his chest, so predicting where you'll end up based on whatever your points or rating is is going to be skeptical at best.