Original Post — Direct link

Source: https://www.bungie.net/7/en/News/Article/update_7361_maintenance


Update 7.3.6.1 is scheduled for release on April 16. Below is a general timeline of that scheduled maintenance:

6:00 AM PDT -7 UTC * Destiny 2 will undergo maintenance.* Sign-on and game integration features will be unavailable on web, mobile, third-party apps, and the Bungie Store.* Players who observe issues should report to the #Help forum.
7:15 AM PDT -7 UTC * Destiny 2 will be brought offline for expected maintenance.* Players will be removed from activities and won't be able to log back in until 10 AM PDT.* Ongoing Destiny maintenance is expected to conclude at 12 PM PDT.
10:00 AM PDT -7 UTC * The latest Destiny 2 update will be available across all platforms and regions.* Players will be able to log back into Destiny 2.* Players logging into the game may be placed in a queue and may experience sign-on issues as background maintenance is still ongoing.* Clan features may remain offline until maintenance is complete.
12:00 PM PDT -7 UTC * Destiny 2 maintenance is expected to conclude.* Console players who encounter issues updating should restart their console and try downloading the update.* Players who observe issues should report to the #Help forum.

Due to complexities with each release, stated times may not line up exactly to release times. For minute-to-minute updates, follow @BungieHelp.

External link →
17 days ago - /u/BNGHelp - Direct link

UPDATE: The game will brought offline at 6:40 AM PDT, not at 7:15 as it says above. This is due to some complexicities with tomorrow's maintenance.