I haven’t seen this officially on the NA Warhammer sites, but the European site says that the Warhammer Online Headstart Program starts on Sept. 14th for Collector’s Edition pre-orders, and Sept. 15th for standard orders. Note that the 14th is a Sunday, so (most) CE pre-orders have a full day of headstart over standard buyers.

But this means that Open Beta is at most 7 days. I guess that’s enough time for some stress testing, but I’m not sure its enough time for many fixes to be developed, tested and deployed.