Scenaturday

Didn't see it mentioned, but this achievement does NOT require that you complete all the scenarios in a single Saturday.

The achievement is cumulative.

This achievement's finally been fixed (yay!), although the way you obtain it is a bit different than you might think. A few notes:

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• The time you can earn this achievement doesn't begin when your server finally hits Saturday at 12am, but rather when your server resets dailies that Saturday morning (effectively 3am Pacific Standard Time).
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• Subsequently, the end time frame is also 3am PST the following Sunday, meaning if you've hit midnight that Saturday, don't worry! You still have some time to earn the achieve (tested this out personally at 1:30AM Central Time, Sunday).
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• Effectively, this means the time frame to earn the achievement is 3am Saturday to 3am Sunday PST. Please note that you can actually earn this achievement over multiple Saturdays.
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Please comment and let me know if anything changes or if I'm wrong about one thing or another.

Edit: Thanks to the commenters Yukidaruma and paladinnr1 below, it looks like it goes by your local time now. Still, remember you can still earn this over multiple Saturdays!

I completed it today, so it's still obtainable. :) You have to go to Vale of Eternal Blossoms, and into the top of Mogu'shan palace. There's a guy named Lorewalker Fu, talk to him and select the scenarios you wanna complete. :) No need for groups, you can solo it.