To stop users from entering time in advance follow the steps given below:
  • Login as administrator. 
  • Select Administration from the top menu. 
  • Select Due/End Dates under Timesheet Setup from the side menu. 
  • Update the values under End Dates section for the specific timesheet period as desired. 
  • Click Save.
Note:
This option can only be set in multiples of 1 month, that means you can only restrict users from entering time for the timesheets in following month. Enter '0' value if you do not want users to enter time 1 month in advance.