Hi Amit,
Request you to look at How PT60 start - ERP Human Capital Management - SCN Wiki
Secondly, the basics are below:
IT0003 PDC date governs when the Time evaluation will start from.
If you have hired the employee from 01.01.2015 and if you have not run the time evaluation at all, and the PDC date is 01.01.2015, then the time evaluation will run from 01.01.2015; it will not matter what you have mentioned in Forced recalculation date in PT60 (Time evaluation).
Secondly, as Sankarsan mentioned, Change the IT0003-PDC date to 01.03.2015 and try that again. but since you have run time evaluation already, the clusters B1 and B2 are updated and now these dates take priority over what will be mentioned in IT0003. Read the above WIKI again for more clarity.
Finally, If you want to run Time Evaluation from 01.03.2015 onwards,
1. Go to SE38, Run the RPUP1D00, enter B1, employee number, your User ID and hit the execute button. select the record, hit delete button.
2. On the safe side, you can also delete the B2 cluster, by executing the report RPUP2D00, same process as above.
3. Change the IT0003 PDC date to 01.03.2015.
4. Run Time Evaluation.
5. Work done !!
Hope this helps.
Kumarpal
Wiki Credits: Woody