We have a very very high tech system for knowing which eggs were laid when (eating eggs, I mean).
I put them in a carton, and the bottom shelf of the fridge is the egg shelf. The cartons go in the shelf from right to left. So the ones on the right are the OLDEST eggs. When I need to grab a carton to give away or use, I grab from the right side and move the onees on the left over to the right. They stack two high, so the bottom right are the oldest, then the ones on top next, then shift over to the left, etc.
Since I give away all my eggs each week (I take whatever we don't eat to church or give to friends) I start over again each Sunday putting the cartons on the right. That way I can also say to whomever takes them that they were all laid within the last week.
Now, when colledting eggs for hatching, I collect them for a week (or until I have however many I need), then mark all the ones set at the same time with a colored sharpie X on one side, and mark in my calendar what group was set on which date. That way when I do a staggered hatch, I know all the ones with a pink X go in the hatcher together on a particular date, etc.
