Add Plan Years with Total Compensation Wizard

I need to extend our plan years and want to do so with the wizard since we have 30 or so plans, but the "Effective Date" is confusing me.  The instructions on the screen state to "Use a date that is a minimum of one year prior to any historical data or the first enrollment coverage start date".  Our plans have varying start dates, some back to 2008.  Does that mean I should enter a date prior to 2008?  That seems odd.