How long does breastmilk stay good for if it has baby oatmeal cereal in it? In the fridge vs. left out

Yes go with the shortest expiration on this for safety, baby cereals are really supposed to be used right after mixing though so keep that in mind, it is safest to just not mix it if baby isn't ready and only do a little at a time to avoid wasting leftovers...

I would go off the expiration of the oatmeal instead of the milk. So I would say 2 hrs at most