Weekend 1 - PlayStation 4 Exclusive:
September 12th to September 13th: PS4 Early Access
September 14th to September 16th: PS4 Open Beta
Weekend 2: PlayStation 4, Xbox One, and PC on Blizzard Battle.net:
September 19th to September 20th: Early Access on Xbox One*, and PC*. Open Beta on PS4
September 21st to September 23rd: Open Beta on PS4, Xbox One, and PC
Specific timing will be announced closer to the start of the Beta.
They said its starts 10 PDT, this is 19.00 in Germany and should be 20.00 in Finland.