Usually starts a week or two before the season. Points in first 3 weeks only count to overall score - so if your playing just to top the league, they don't matter till round 4.
Apparently it opens on Monday, so can't wait for that. Seems to be a bit of talk you can enter your team into 3 leagues. Which would be good, got 11 spots to climb this year to win supercoach. Although it will be pretty hard to do that I think...but who knows