Display values based on earliest date selected

I'm trying to find the first value after the start of a range. The request was for the rank difference over the last year, so I created a series of measures and calculated columns to first define the date 1 year ago as StartOfRange and then find the first value after the StartOfRange and that is what showed up in the (Blank) field below. That wasn't nearly flexible enough and sure enough the user tried to change the date page level filter to something more recent and that errored out of course because the rank that should be displayed here occured before the new page level filter date. 

How do I do the equivalent but based on a page level filter instead of 1 year ago today? Or is there a way to use the earliest date in a sliding date slicer to do the same thing?