Start with two buckets for brass. Label them #1 and #2.
Put new brass into #1 and start loading it. Label each container of loaded ammo #1.
When fired, put the brass into the container marked #2. Continue loading and shooting #1 and putting its fired brass in #2 as long as any brass is available in #1.
When gone, start loading #2 and marking the loaded ammo containers #2. When you shoot #2, put its brass into a container marked #3, and so on.
For multiple headstamps or different batches of the same headstamp, you’ll need to record batch numbers on brass containers and loaded ammunition as well as the number of firings.
This way you’ll always know just how “used” each and every piece of your brass is.
And, yes, this means I have two containers for each purchase of brass. (I buy at least 1000 pieces of brass at a time and use plastic storage containers with lids from WalMart that are stackable.)
After 4-5 firings, everything ends up in a “Many fired” bucket that is used only for practice. I reload the shells from that bucket until they split or are lost.