For me at least, "stocking up" is a continual process. I already have a year's supply of food and other essentials, so it's simply a matter of rotating stocks, using the oldest on a daily basis. If you aren't already at this point, getting there is relatively easy. Whenever you go to the grocery store, if you're going to buy one of an item, buy two instead. Decide what canned goods you can make a meal out of, and buy a couple of them too. Be sure you write the date on each item you buy.
Do this, and you'll be surprised how quickly your stocks will grow. And if you don't do this, after we've warned you, well...
Onward and upward,
airforce