how to lock time sheets of current month after specific date

[silviocrive]

I need to lock Time Sheets with date "Week starts on" in current month, after a specific date (if possible configurable for each month/year). 

Time Sheet Users and Approvers manage Time Sheet by Time Sheet Portal.

Suggestions according ServiceNow Best Practices are more then welcome.

[Tanushree Maiti]

Refer this : Freeze Timesheets Dynamically

How to restrict user to submit or edit timesheet older than the Current year