Dark Souls II will unlock on Steam at the following times:
4/24 – 3:00 PM PDT
4/24 – 6:00 PM EDT
Make sure you pre-order on Steam before then to get your digital bonuses!
You And, in case you missed it, you can also take a look at the Dark Souls II television commercial that made an appearance during The Walking Dead Finale.
Source: Bandai Namco Games