Here is the timing for the open Beta Cod Vanguard  Then, starting on September 18 at 1 p.m. Eastern, all players will gain access to the Vanguard beta, regardless of whether or not they have pre-ordered the game. This period lasts until September 20, so you'll have a couple days to check it out.

Kevman has kindly made a video on how to get the beta

http://www.politeandfriendly.com/audio/How%20to%20download%20Vanguard%20Beta.mp4