How can I get all outstanding timesheets through the approval process so that I can run payroll?
Make sure the Enable Administrator Bulk Approval - Timesheet property is turned on under Admin > Properties > Approval Process > Approvals.
On the Admin > Setup > Time > Time Periods > Search tab, select the Include Option to Complete All Pending Approvals for a Time Period check box.
On the List tab, there will be a blue circle check mark beside any time period that has timesheets in approval queues.
Note that this does not include MISSING timesheets that have not been created for a given time period, nor INUSE timesheets that have not been submitted.
If you also need MISSING or INUSE timesheets to be created/submitted/approved, you will have to do this for each user on the People > List page (clicking on the list timesheets icon for each user). You should create and submit these timesheets prior to running the Bulk Approve in order to save time.