WDV Depreciation for Existing & Newly added Assets

We are using EPBCS Out of box functionality

I am trying to calculate Depreciation for existing & new assets using Custom Depreciation method (Written Down Value) and convention as Prorate Actual Date. Is there a possibility where I can define formula for WDV depreciation method and based on that it will calculate depreciation from the Out of box Business Rule.

I have written Custom Business Rule which is calculating Depreciation for CurrYear and Budgeting Years same has to be done for the Prior years.

For Example:

I have a Asset with In Service Date : 26-Nov-2016

Depreciation should start from the same date but in the current rule it starts from 26-Nov-2021 and this go ahead for next 5 Budgeting years same in Forecasting.