Hi,
I think you are looking for Lag Scenario in BW, which is common w.r.t APO.
Follow the steps as below:
Here Lag is just a difference of Fiscal Month and Snapshot month.
Pre-requisite- Ask the APO team to get you fiscal month from APO side then based on system date you can have snapshot month.
Let me know if this helps you.
Regards,
Mayank