Digital Download Question for Cataclysm

How will the digital download work? Will be be able to download before midnight and install at midnight pst, or is it delayed for people who digital download? I only ask because my husband and I are military and living in Germany, and we aren't yet positive if we will be able to get the game on release day here or not. We only have one store here that we can get the game from and we happen to live in the largest community of Americans outside the US, so there will be a lot of people trying to get the game from this one store. And no there is no "pre-order". Planning on using Digital download as a back up plan, and just trying to find out how it works ahead of time.