Dating your boxed eggs?

May I ask those of you who sell surplus eggs in a roadside honesty box what the advice is on marking "best before" dates on the boxes?

The reason I ask is that a new local chicken owner started selling their spares near me last summer and still has the odd 6-box of mixed chicken and sometimes duck in their roadside box at the moment. Since my regular person is off-season just now, I had a look at the new folks and picked up a couple of boxes. What struck me as unexpected was the BBE of only 12 days away. The owners were not present for me to ask about it.

I am used to around 4 weeks as the typical dates on boxes and thought it odd that they would have such a potential surplus in mid-January that they couldn't shift them all and might be running up to their date. They only appear to have about a dozen birds so it is not a large scale producer by any means.

When I got home I put them in the fridge (since they will be fertilised - the rooster was staring at me while I was at the roadside box).

I inspected two of the eggs today and think they are actually very fresh indeed - only a few days old. They have a clean shell, bright yolk and the white shows a distict difference between the thick and thin which is what I usually associate with an egg in its first week or so.

So... what is the typical BBE range that you are advised to use?

Thank you - I expect they are releasing the eggs in batches when they are likely to be in the property to keep an eye on the box. That probably means they accumulate eggs until they have a decent amount to put out. As you said, the "oldest" egg sets the date for the rest.

I am sure I will bump into them at some point to ask.