Shadowlands season 1 starts today, opening up the expansion for some more engaging gameplay. Week 1 & 2 has mostly been about preparing for week 3.
As season 1 starts, the Castle Nathria (normal, HC and Mythic) will open up, along with Mythic Keystore Dungeons and the PvP season.
Blizzard recently posted a survival guide for season 1 that you can see below.