Hi Narsimha, here it is
right click on Session name -> press 'Edit' -> in propertie tab 4th is Enable test load - tick it and - 5th is no.of rows to test - type as 1000. then press OK.
But wth this option you will not be able to check the data in the target table.
You can manually stop the session after loading 1000 rows into Target table. (Don't choose Test Load option).
Go to Workflow Monitor -> right click for properties on Session - > once you see target success rows as aropund 1000, then once again right click on session - you will have option "Stop", press it.