Define not overlapping date ranges for your payroll periods. The periods can be of any length and can start on any arbitrary day. For reconciliation it is advised that the Timesheet first day of the week matches the payroll period (e.g. Sundays, Mondays, etc.).
If you have payroll period with overlapping date ranges, an arbitrary period will be selected. You would create a payroll period with the same date range for adjustments after you closed and reported the original payroll period.