Since after 70 views there is still no answer I'll try to ask the question in a bit different way.
Is there any way to track how many periods in a given month a certain user still has unapproved/not submitted?
So that system will show the count of weeks with status different to 'Posted'.
Lets say that I have registered the time for 27-30 of November and forgot previous November's periods.
How can I take out those not submitted weeks for November for a certain user?
It should probably show number '4' as we had 5 Periods for November, and one would be approved.
Additionally, what does the 'Missing Timesheet Period Start/Finish date' stands for?
Can I use that value to take out the data that I need?