@winterfelllvoyager75 I always use a fine tipped Sharpie to write the month and year on my Aerobika parts. This is the starting use date.

After six months, I get a new pair of Aerobikas and place each of the old sets in a zip lock bag and label the dates used. They are extras and come in handy to use when not home because I can rinse them and then wait to sterilize when I return. I leave the newest ones at home. I do the same for my Pari LC cups.