Hi Manoj.
For asset transfer from legacy to SAP is two step process:
1. Transfer Asset master data and subledger values
2. Post on reconciliation account
For the above first setup the asset transfer date in spro:
Asset accounting >> Asset data transfer >> parameters for data transfer >> date specifications >> Specify Transfer Date/Last Closed Fiscal Year
In case of mid year migration you need to maintain values in Specify Last Period Posted in Prv.System (Transf.During FY).
Then you need to write an LSMW to create master data and subledger values (Transaction code AS91). The data source is legacy system and field value mapping like asset class, cost center etc.
For posting on reconciliation account using OAMK transaction code to remove the asset reconciliation indicator and then post using FB01 or F-02.
Regards,
Ritesh