I'm sure it's better to pull on an empty stomache. But.. many times like you I wake up hungry, chomp on something or other and then remember about OP... like today for example.
I OP'd afterwards and feel pretty much like I usually do after an OP. Mouth clean, gums good and skin infused. I wouldn't recommend it directly after a "Super Slam" breakfast or anything, but even then I don't think it'd hurt anything.
OP is very benign - not doing it by the book usually won't be a problem and still give benefit. The only thing I think you really need to be careful about is the rinsing afterwards.