Oatmeal Mash

Gonna try a stout soon that I would love to add flaked barley to, but my homebrew supply place doesn't carry it (I'm in Korea). So I'm going to do a cereal mash with some raw oatmeal. I've done this once before and it worked out well, but as my kitchen is very small I don't want to go through trying to do both the cereal mash and the main mash at the same time again. So I'm wondering if there is any reason I couldn't do the oatmeal the night before and then throw it in the fridge until the morning. I'd most likely just keep it in a covered pot and then reheat it just prior to throwing it in the mashtun. Seems pretty cut and dry to me. Is there anything I'm overlooking?

Unless they are oat grits, I don't think you need to precook the oatmeal in any way. You can add the oatmeal to the mash at saccarification temperature. If you employ a protein rest or beta amylase rest, wait until you're at amylase rest before adding the oats. Too much stirring breaks up the oats and develops beta glucans into a thick, gelatinous mess that won't sparge well.

That said, if you feel you need to precook the oats, by all means you can do it the night before. Just add a little boiling water to heat and loosen it up a bit before adding it to the mash.

Sorry. I should have said "oats" and not "oatmeal".