First Date is the earliest date on record. Click First Date will re-generate a report for that date. The Date of the report appears at the top right of the report.
Prev Date is the (previous) Day, earlier than the current day. The Date of the report appears at the top right of the report
Prev Shift is a Shift earlier than the current Shift you are viewing.
Next Shift is the Shift after the current Shift you are viewing.
Last Shift is the Last Shift with any data. This is usually the current date and current shift.