Can the TS Approval Manager review the timesheet prior to actuals being applied?

Yes.  First - you must confirm that you are assigned as the Timesheet Reviewer for the resource.  Second - you must execute “Tools…Time Approval” from the Project Management application to review and/or reject timesheets.  The timesheet for the previous week must be rejected before 1pm on the following Tuesday or else the labor hours will be applied to your project(s).