Fetch lowest available Fisc.Period from Bex datasource

Hi Experts,

My datasource(Bex) initial view is like below. Measures are in Rows, Fiscper is in Column

                        001.2013     002.2013     003.2013

Sales

Revenue

There is a chart which displays from the above DS. Now i need to somehow fetch the lowest available period. It can change depending on the Filters applied by user at runtime, say, for a Region or Comp Code. As seen above, the period i need is 001.2013 which will be updated in a Text Box. The starting period could be 001.2012 or 001.2011 as well for some Region or Comp Code.

Any ideas on how to accomplish this in Design Studio ?