Control range in a line chart by hiding/unhiding data columns using data validation lists

I would like to use two data validation pull-down lists to hide and unhide columns to define a chronological range on a separate sheet file ("Data"), with the ultimate goal of allowing easy control of the start and stop dates of a line chart on the "Dashboard" sheet file. Each listing in both data validation pull-downs is an annual quarter with a year date ("Q1-2015", for example). By selecting a later date in the second pull-down list, the correct chronological columns in the "Data" sheet file will hide or unhide, and thus the timeframe of the chart in the "Dashboard" sheet file is adjusted. The columns have headers with matching titles "Q1-2015". I'm familiar with many VBA terms but not fluent with Hlookup or Match, Index, etc., and not sure where to start.

A second condition is that the Stop date in the second validation menu can never be earlier in time than the Start date. And vice versa.

Attached is a mock-up of what I am trying to create.

Any ideas out there? I appreciate your help. Thanks. David