Idea: It might make sense to group by year or by year/month. This would give you groups that contain books within that period. The choice would be made by how many different groups you end up with. Getting too specific with the date will devolve to groups of one book.
If this is something you might want, then create a new custom column 'made from other columns'. Set the type to text. Do not check "Show in tag browser". Set the template to something like
Code:
{#updated:format_date(yyyy-MM)}
where the date format is the granularity you want. The above example gives you year-month. You must put the date components in order from most significant (year) to least significant (seconds). Add the lookup name of the new column to CC's group-by