Or will it get weird ?
do it! I'm pretty sure it will get even better in that eight hours
Sorry Sarah, it won't. The baking powder will continue to bubble and brew and the end result is very likely to be tragic, if not inedible.
This is not ideal. The baking powder is the leavening agent. Once you combine it with an acidic liquid, it starts to form bubbles (carbon dioxide) which is what helps the dough rise when baking.
When the batter just sits, the chemical reaction continues, but some of the air bubbles escape and over time, the bubbles will collapse.
There are two types of baking powder. Single action baking powder starts with the mixture of the baking powder and acidic liquid (buttermilk in this case). Double action has a second reaction with the application of heat. For something like a pancake, you can get away with mixing the batter several hours in advance with double action baking powder, but it is not ideal.
There are two alternatives. First is to have your mise en place done ahead of time and make the batter shortly before baking. The second option would be to combine the liquid ingredients together and the dry ingredients together; combine the two shortly before baking.
Either method will result in a superior end result than preparing the batter early.
I wouldn't do it. There's a very good chance that you'll lose all the leavening while it is waiting and will end up with an unappetizing mess. Unlike yeast breads, quick bread batters don't improve with a rest. What you can safely do is premix all of the dry ingredients then add the moist ones right before you bake it.
I did that once... Grey and bitter. Not worth the perceived convenience. cv has a better way.
Ok I'm back. Here's what I did. Combined dry ingredients in a bowl. Added wet stuff in the evening. It was very fast. I decided the biggest problem with getting the cornbread on the table quickly was the need to preheat the oven! That slows things down a lot.
I mean, I combined dry ingredients in the morning. Left it there and added wet stuff at dinner time.
Yes, waiting for the oven/stove,/pan to warm up or water to boil is often the bottleneck. I have a conventional electric range with electric oven, so things heat up/cool down slowly. If I arrive home hoping to bake/roast something quickly, the first thing to do is to preheat the oven. While I've never carefully timed it, my oven probably takes 10 minutes to reach each 100 degree mark (e.g., 30 minutes to reach 300 degrees).
Also, if I need to boil something, I start boiling water when I walk into the kitchen. You can cut a few minutes simply by drawing water into a stock pot ahead of time, leaving it on the stove, then turning it on when you need it.
Anyhow, hope the cornbread was tasty.
I find that a 15 minute rest of the batter helps to achieve a maximum crown when making cornbread muffins.