First Date is the earliest date on record. Click First Date to 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 report you are viewing. The Date of the report appears at the top right of the report
Next Date is the Day after the current report you are viewing.
Last Date is the Last Day with any data. This is usually the current date.