The majority of my egg cartons are recycled. My customers bring them back to me when they need a refill. I found some small, rectangular post it notes. As I start a new carton, I write the date I started it on a post it and attach it to the top of the carton. When that carton is filled I write the end date on it. That way there's not a bunch of old dates to cross out on the carton itself. Much like ranchhand does.