Since people would give me their clean egg cartons I would just hold onto different colored ones and I knew that white was the oldest, then pink, then blue then cardboard. Before I had colors I just wrote 1,2,3,4 on the cartons and rotated them accordingly. If the egg was too big to fit in the carton it went in my "big egg" bowl and I used it up before the others.
Obviously I had room for 4 cartons in the fridge, my new fridge only fits two at a time. But I usually have at least two or three dozen setting out in a cool place to "age" on the counter. Those I use for hard boiled eggs after they hit the 14 day mark. I sometimes have an egg customer request the older ones if they are planning on doing any hard boiled ones.
Obviously I had room for 4 cartons in the fridge, my new fridge only fits two at a time. But I usually have at least two or three dozen setting out in a cool place to "age" on the counter. Those I use for hard boiled eggs after they hit the 14 day mark. I sometimes have an egg customer request the older ones if they are planning on doing any hard boiled ones.