Somehow I think the TWs Closed beta release won't be for more than a week. Two at the most. Then Open Beta.
Reason: The only thing I can think of for doubling or tripling (at least) your invited playerbase is to stress test the server browser and mass test. I don't think that's going to take very long.
Hopefully they'll release it to open beta before FogieLAN, (28-29 July would be perfect for this, hint hint nudge nudge...) but if they don't it's not really a worldkiller deal. Thing is, even if they have two weeks of closed beta after TWs, there's the question of why they are going to have almost 2 months of open beta (August, September, release in October).