Chromie time is intended only for leveling characters. Once you reach level 50, it is disabled for your character.

While this event is active, players level 86 or higher may access a special Timewalking Dungeon Finder queue, which scales players and their items down to revisit past dungeons from the Cataclysm expansion. While Timewalking, bosses will yield loot appropriate for a player’s natural level.

When: The Ulduar raid is available throughout the Wrath Timewalking event. Difficulty: The difficulty is set to Normal and, like any Normal level raid, will not be available through Raid Finder. Minimum Level: Players level 30 and above are Eligible to participate.

Timewalking dungeons drop Item Level 184 loot. You can get Item Level 226 loot from the Black Temple Timewalking raid. Reins of the Infinite Timereaver has a small chance to drop from all Timewalking bosses as Personal Loot.

Timewalking Campaigns are available for you to use as soon as your character reaches level 10 or completes the new starting experience, Exile’s Reach.

Timewalking is available for characters level 50 and up.

For item level 200 gear, complete all Shadowlands dungeons at Mythic level five or higher. For item level 207 gear, complete Mythic dungeons at level 10 or higher. And for item level 213 and higher, complete Mythic dungeons at level 15 or higher.

How many times can you extend a raid lockout? (i.e. extending an Ulduar raid ID will add 7 days, a Heroic: Halls of Lightning dungeon ID will add 24 hours, and a Zul’Gurub raid ID will add 3 days to the lockout time). An ID can be extended more than once.

Kiatke is the Cataclysm Timewalking vendor, found in Orgrimmar and Stormwind.

https://www.youtube.com/watch?v=pM-jp77D1ZE