frugalparagon - we make two mornings worth at a time - do you stretch it out more than this? It would be great if you could make the whole week, assembly line style, on Sunday night. Would Friday morning's fridge oatmeal be...dodgy?
I've experimented with this, and it does get pretty nasty after two days. Plus, if your schedule changes at the last minute, you have all these premixed oatmeals going bad in your fridge.
I've found that an easy solution is to mix up the wet ingredients (milk, yogurt, honey, apple butter, whatever...) in the individual jars on Sunday night. Then I measure any dry ingredients (oatmeal, flax seeds, nuts, dry fruits such as blueberries) into either a reusable container or sandwich baggie which is placed atop the jar in the fridge to be mixed in the night before use.
It saves a good bit of time from not having to measure ingredients and wash measuring implements every night. Also, if one of your target consumers (ahem, DH) is averse to eating the same flavor of oatmeal every day, you don't have to be inventive at the ungodly hour of 4:00 a.m.