Hi Yadagiri,
You can assign time based disaggregation to the key figures in your planning area via transaction - /SAPAPO/MSDP_ADMIN.
In SAP APO 4.0 and above, changes can be made to the key figures in an initialized planning area without deleting time series data and thereby loss of data. Here, you can go to Change key Figure Settings and assign required time based dis-aggregation method like P (Pro rata), E (Equal) etc as per your requirement.
You can also refer to below link - it will help in understanding how system performs dis aggregation internally -
Example of Disaggregation and Rounding - Interactive Demand Planning - SAP Library
Hope it helps.
Regards,
Alok