You should know that the best before date for an egg is 4 weeks after laying.
A well-known trick to tell if an (uncooked) egg is fresh is to put it in a glass of water.

As the egg ages, the liquid inside the egg evaporates and absorbs air.

The air chamber of the egg then becomes larger and acts as a float.
To be sure if you can eat a floating egg, it is recommended that you break it open and smell it.

If it smells of sulphur, do not eat it.