The slam comes later in the beta, on a day that is not set.
- Week 1 of the beta is Skyborne and Zephras Isle, plus all zone content up to level 20.
- Week 1 dungeons: Hall of Thanes (13 to 18) and Ruins of Lordaeron (15 to 20).
- Additional zones, dungeons and the new battleground open for testing as the beta continues.
- 24 Sep is the next full weekly client update, not the slam.
Unconfirmed the slam's day and length, and which zones and dungeons open next and when.
Source Blizzard's Forever beta post.