A simple tip to check the freshness of eggs
Place the egg in a large glass of cold water. If it sinks to the bottom and lays horizontal on the bottom it's very fresh.
If it sinks to the bottom but sits up a few degrees at an angle it's probably about a week old
If it floats anywhere away from the bottom or sits in a vertical position then its stale & should not be used.
This simple test works in 99% of cases....the only time it won't work is if there is a hairline crack in the egg.
I think it's best to use eggs within 2 weeks but as always...... the fresher the better
Steve