While Destiny 2 is set to launch at midnight (local to your region), the game's servers have gone live across the globe! This means that anyone with a physical copy of the game can play. If you pre-loaded a digital copy or own a digital copy altogether, will have to wait until midnight to play.
Unfortunately, it won't be launching with all of its features. One of the features that will not be making the launch are Destiny 2's Clan Features. According to Bungie, these features won't be available for the "first several days after launch."
In addition to Clan Features being delayed, the Raid will kick off at 10 AM PT / 1 PM ET / 6 PM BST on September 13 and Trials will be available at 10 AM PT / 1 PM ET / 6 PM BST on September 15th.
Other than the Clan Features, the Raid, and Trials, Nightfall Strikes will be available in the game from the get-go.