I would avoid flossing prior to eating, given the potential for food bacteria to gain foothold if the flossing had any bleeding associated. _Prior_ to eating, I might to a non-toothpasted brushing to just get any gunk accrual off, but: no toothpaste (to avoid affecting flavor) and no flossing (to avoid potential infection). _After_ dining, however, flossing and mouthwashing it clean, followed by a toothpasted brushing would be ok.
I floss in the morning and night when I brush my teeth and sometimes midday if my teeth need it. Dentists recommend brushing/flossing after eating anytime