I've always brushed my teeth before breakfast
After, Mint flavoured milk and weetabix stuck in my teeth sounds annoying.
I brush in the morning after breakfast and in the night before bed, like any normal person.
Interestingly though, I do wash my hands before and after peeing. People are always worried about the germs that get on to their hands but they forget they are also putting germs on their crotch when they get it out.
Afterwards - why would you brush your teeth, only to immediately eat again?