i would definitely go to costco or somewhere that has a lot of perishable supplies. But just keep in mind that a lot of the food there is refrigerated and you wouldn't be able to live off of that for more than a few months.
One of my official plans:
1. Get all food from my house that won't rot. Put it inside of my parents' car.
2. Get my parents to bring along some things that could be useful for barricading off possible houses.
3. Get the forget out of my apartment building.
4. Follow the news on my phone. Get a mobile charger for the car.
5. Costco
6. Costco gas (Fill up until the last drop. Then flee.)
7. Go to Nevada (Preferably away from Area 51, but as rural as it gets, where there is no possible population)
8. Barricade it off.
9. Go to Rachel, NV, see if there's any food left.
10. Go around Area 51. See if there's a way in. If so, STEAL ALL THE THINGS! Hopefully.
I had a dream about this once, and it was really eerie. I woke up on the street I used to take to go to school every morning, in a car. We pulled up into the Publix parking lot and grabbed what supplies we could, then loaded onto a large boat, crowded with as much people as possible. Didn't seem very safe. It began to rain, and the streets were flooded. I kissed what I had known as Jacksonville goodbye, and we were almost there. Then, we arrived at the airport - Jacksonville Int'l. Oddly enough, many flights to Africa were running. We all boarded a refugee flight towards Africa (Jacksonville gets like 1 international flight a month, and no airline flies towards africa anyways but forget it, it's a dream). We were packed onto a refugee camp upon arrival and we had to find people. Once we did, we had formulated a plan. Get out of the camp, and run to the nearest airfield. Then at the airfield, book a flight to the only clean city in the world - the walled off Chestryka, Russia (not a real city). There, we got into a cop car and drove home, safe at last.