Any idea how to write a Validation Rule, that prevents the user from creating more than one record a day.

I have one Object called `(Stundenkonto__c)` it shows a Month in Timetracking.
I have a Object called `(Zeiteintrag__c)` it is the Master Detail of (`Stundenkonto__c`)
So the User should only be able to create only one (`Zeiteintrag__c`) Record a day.