You can follow below steps.
1. create and insert "month id's/month" into a backend table.
2. Then in your qvw script write a query to select & consume the top row from the above created month table and store this into a variable.
3. use that variable in your QVD extract qvw file.
4. copy paste the above qvw file for 12 times. and create the 12 tasks in QEMC.
5. run all these tasks parallely.