However, you can create a line item that is formatted as a time period (Months) and publish that to the dashboard. Then you can check that line item using the IF ITEM(TIME) = Selection module.Choose month
If you need the use to only select certain months (so either Jun or Dec), you'll need to create a list with those two members, create a module by that list with a line item that is formatted by month.
the the check will something like:
IF ITEM(TIME)= Choose months.Month[LOOKUP:selection module.Choose month]