At what point Service Tax Credit can be claimed.

when cheque is cleared i.e. debited in payer's bank a/c , CENVAT can be claimed

Credit can be claimed in Feb 2007 and can be utilised for payment of liability in the month of March 2007. Mere making the payment will not make you eligible for the credit, though you may account for in your books, but utilisation can happen only when the payment has been realised by the service provider and your bank account has been hit by that amount