I am baking cupcakes for my son's school's event on Friday and attending a local bake sale event the following Sunday. I am thinking to mix all the batter on Friday morning, bake half of the batter for my son's event, refrigerate and bake the rest on Saturday for my Sunday bake sale to keep my cupcakes fresh for my bake sale on Sunday. Would you recommend me doing this?

some people do -- no problem -- i've seen it done in commercial work -- but i would not do that myself unless i'd fully tested it advance -- i would however measure out everything needed on the friday so half is getting mixed that day and half is right ready to be tossed together and mixed saturday --

K8, I have done that myself too. I always mix up all the dry ingredients needed for a cake then put it in a zip lock bag so it would make it easier for me and of course leave out butter and eggs. If using buttermilk I leave that out for at least 2 hours to get to room temperature. I also had my parchment paper already cut and had them sitting in the cake pans I was going to use. 

The real reason people don't do this more often is because the main concern is the leavening (ie. the baking powder, baking soda, etc.).

Both baking powder and baking soda have a reaction and produce air bubbles in the batter as soon as they're mixed in. If you leave it sit for hours, even in the fridge, these air bubbles will probably settle out and you'll lose some of the rise to your bake. So with baking soda, the process ends there with that initial reaction. With baking powder, however, there's a second reaction to the heat of the oven, creating even more air bubbles. This is why baking powder is labeled as double acting.

For that reason, it may be possible to preserve a cake batter that relies on baking powder. But you'll still probably lose some of the leavening.

If you're not a scratch baker and you use cake mixes, those rely a good deal on baking powder, so in theory you might be able to pull it off.

In practice, I'm not so sure. My cake shop I work at uses both box mixes and larger commercial bag mixes, and none of that cake batter seems very appealing after it's been sitting out a while. It just gets kind of funky after time. Our rule is that if you've mixed it, you have to make something with it, we don't save it for later. Usually we make the cakes we need for production, and then kill off the remaining batter with cupcakes.

I froze batter once and made cupcakes that turned out good., but I only made them for family.

i now bake any cake batter I have left into cupcakes and freeze them. I have froze them both iced and not iced. Depending on if I can get the container in the freezer once they are iced. I have left them in there for a month and when I am ready to use then I just set them out to defrost. They have always tasted like they are fresh. I have coworkers say, I can’t believe you were up all night baking. So if you have room in your freezer you might want to try freezing them.

Good luck!

remnant -- you're a first class baker