The DLC will launch alongside a the arrival of Destiny 2 version 1.1.0 which introduces a host of new changes - here's everything you need to know.
Lastly, you will be able to play Destiny 2 Curse of Osiris immediately after the servers are back online. We know little more about the release dates for either DLC expansions right now, but we'll make sure to keep this guide updated with any and all future information. These include the planet Mercury, the Vex-controlled Infinite Forest, and the Lighthouse, which is where the Followers of Osiris wait for the warlock's return. That is the official Curse of Osiris release time, but it could be early or late depending on how this all goes.
Rally your fireteam and enter the all-new Raid Lair, Eater of Worlds. While not as lengthy as Destiny 2's Leviathan raid, it will contain new puzzles and encounters that pose just as much of a challenge. Curse of Osiris is likely to come with a large update, and it's best that you get that installed before you get home and want to play.
However aside from this, the majority of the datamine of Destiny 2 on PC uncovered concepts that could be used in future Destiny 2 DLC expansions, or not at all. The Prison of Elders is also briefly mentioned at one point, along with the Crimson Days, the Dawning, and the Festival of the Lost (the Halloween event).