Wow, a whole week at King Arthur, that's very cool! Wonder if the tables there are all round...

I often make up a pancake or waffle batch and let it reside in the fridge for future use. But I will ask the source, as I am heading up to King Arthur for a whole week of baking classes! Will get back to you in about a week or so!

Sourdough waffles on kingatthurflour.com

What mix or recipe are you talking about? With many recipes you can refrigerate a mix overnight, but let us know which recipe you are referencing and we can be more helpful.