Recommendation for Costco Trip

If I was doing a 2-4 week supply then I would look at what you normally eat and stock up a 2-4 week supply of that. Bear has several videos that talk about food storage and the 7 day meal plan. Water is a necessity and you want at a minimum 1 gallon per person per day times the number of days you are planning for. Short term storage of items you normally eat and make this your working pantry to rotate your food items out of. Then medium term storage and then long term storage. Just my 2 cents. Do the things to learn the things.

You're doing fine. Buy 20 gal of water and buy more every time you're at the store. Not necessarily 20 gal every time, but just keep buying more. :) Rice, Beans, Corn, Wheat Veggies. Lots of this stuff can be canned stuff that will get you up to a 2 year mark. If you really manage your expiration dates you wouldn't really need to buy that much bulk dry food. I like rice and beans too much and have lots of dried on-hand. Go through a list of stuff that you eat on a weekly basis or monthly basis. Note what you are running out of and keep having to go to the store for. Buy a ton of these when they go on sale and get them from your pantry instead of having to make a trip to the store. Pull from the front and restock from the back. You know you're doing it right when you don't have to run to the store for anything that you're out of. You go to your pantry and eat that. You replace your pantry. Then you expand on making your pantry last longer and longer and longer.