For EU? Starts soon after tomorrow.
Sadly timewalking is still borked. Mobs that take more time to kill than Mythic at appropriate gear level.
Panser said that the dungeon is scaled to the players, this is an oversight on her part, they actually scale you DOWN to the dungeon, which includes slashing your stats all over the place. So, not only does it take longer to kill mobs, it can feel like a struggle uphill as you dont have all your normal stats at the appropriate levels.
Yay, get two more mounts - The camels!