I have done the "Jack Method" along with simply taking advantage of good sales on various items. For example, if canned green beans are on sale I might get one or two cases. (We eat a lot of this. Probably at least 2 - 3 times a week.) It is indeed amazing to realize one has a year's supply of paper products, personal hygiene products, vegetables, spices, etc. while one is working on getting to that mark with other categories of preps.
I'm now in the midst of reorganizing my stores for better inventory control. I usually write the year of expiration on the lid of canned good with a permanent marker so it's easy to see. This makes rotating stock a little more likely to work the way it's supposed to (ha, ha).
I also keep an Excel file on my computer of my supplies.
Just my 2 cents' worth.