feed it whenever it wants to eat. its really and truly that simple. you can keep all the defecation records you want, but ten rooms full of filing cabinets will not change the simplicity of the fact - open the cage, offer it feed; if it takes it great; if it does not, so what - it will eat when its good and ready regardless of your chart keeping skills. same with defecation.
as long as yr husbandry is correct, they dont care about your perceived schedule... give them water, give them food, they poop when they poop and they eat when they eat. not unlike you or i... and not fitting into our neat and orderly view of how things should be is exactly what balls live for.