I always make my shopping list  as early as possible, I highlight perishable, so I can purchase things when they are on sale.

 

I put stickers on my camp food to make sure they are not used, (the rule is if it gets used early the box is left on the counter so it can be replaced.

 

I buy dairy and produce a few days before my campers arrive. If you lack storage space to buy ahead start a savings account or buy gift cards at your grocery store.