DEAR MISS MANNERS: I understand and observe the rule that one should wait for everyone at the table to be served before one starts eating, unless the not-yet-served parties demur and urge others to eat.Is it also considered necessary to wait until others have photographed their meal and posted it to social media?This issue arises for me not in restaurants, but at home. My husband and I split cooking duties, so we each cook on different nights. He tends to make elaborate, time-consuming spreads, of which he is justifiably proud.