In Blizzard's Weekly Scheduled Maintenance article, it has been revealed that Diablo 4 servers will be down for maintenance from 7:00 a.m. — 8:00 a.m.
PST tomorrow, October 17th. This maintenance period is set to take place just hours before Season of Blood goes live at 10:00 a.m. PST, which indicates that Patch 1.2.0 should be available to play once servers come back online at 8:00 a.m.
PST.
Blizzard's Weekly Scheduled Maintenance Diablo 4 Season 2 Gameplay Trailer
While players will not be able to see all of the new content coming to Season 2 until its release at 10:00 a.m. PST, all of the quality-of-life and non-seasonal content in Patch 1.2.0 should be available to play immediately on the Eternal Realm.
What To Do Before Season 2 Diablo 4 Season 2 Twitch Drops