Darkmoon Faire starts on Sunday and if you wait with your weekly quest turn-ins until then, you’ll get 10% more reputation.
If you’ve already turned in the “Aiding the Accord” quest and the World Quests weekly this week, you’re out of luck, but if you haven’t completed them yet, you can wait until Sunday when Darkmoon Faire will start. The WHEE! buff increases reputation gains by 10%, so you will end up with more reputation from both the weekly and bonus event quests.