I have to update my kits pretty often because my kids grow out of their emergency clothes so quickly. But at those times I just exchange clothes. I like to update the food in my kits every 6 mths because my food like granola bars, dry fruit, etc, start to get hard. If you have MRE's and such in your kits than they are going to last longer. I have listed different ideas in this blog as to what you can put in your kits. I chose a variety if things that I don't have to cook, my kids will eat, and light to carry. When I replace the old food with new, I put the older ones in the kids "snack drawer" or for cold lunches. I only threw out some raisen boxes this year that got really hard.
On the right side of this blog, you will see links to help build your 72 hr kit. Start with finding the right container to put everything in. Take it at the pace that works for you. Whether it is getting an item for each kit once a week or once a month just get started!
It really doesn't need to be overwhelming! Start simple with a 72 hr kit and get the basics and work from there:)