MDX Query Parameterization for displaying Last 12 month's SSRS Report

While working with SSRS reports for displaying some financial data; many a times we have to display data for particular time-frame. Or most commonly - last 12 month's data.

I am talking about the case where you are pulling data from SSAS Cube using MDX queries. In this particular example, I need to display SSRS report for last 12 month's data from SSAS Cube. So I need to provide 2 things: StartDate and EndDate.