Choosing a grocery is now like choosing a bar. You do not just stumble in to any store lest you have to endure the wrong kind of people. And, you have to pay attention to when you go. Tuesday at 10AM is a great time to buy baby food. Meeting women? Not so much.
Saturday and Sunday afternoons tend to be families out shopping. Evening rush hour is easy to spot singles just off work grabbing something to eat for the night.
Sunday night and other 8pm+ times seem to be more singles stocking up. Unless it is an emergency provision, most families are at home by then.