In somewhat unexpected news, Blizzard has announced that both the North American and European Overwatch beta event will kick off on Tuesday, October 27th. Originally, the beta start was to be NA only, but Blizzard revealed late last week that the EU version would start simultaneously.
We were able to complete setup and testing of our beta servers for Europe sooner than anticipated. As a result, we're happy to report that we will be launching the Overwatch Closed Beta in both the Americas and Europe gameplay regions on October 27.
Source: Overwatch official site