https://www.polygon.com/2018/8/14/17690546/call-of-duty-black-ops-4-blackout-beta-dates

Call of Duty: Black Ops 4’s take on battle royale multiplayer modes, Blackout, will be playable for the first time starting Sept. 10 during a limited beta, Activision and Treyarch confirmed today.

PlayStation 4 owners will get the first crack at the Blackout beta. It’s not clear yet when players on Xbox One and Windows PC will be able to jump in, but Black Ops 4’s first multiplayer beta was on PS4 a week ahead of other platforms.