cenvat credit

company A has input service tax credit of Rs. 2 crores in month of april and may 09 it has parked this amount in the clearing account the company has substantial credit of capital goods

queries

is it required to avail the credit by posting from clearing account to availment account and then is it required to utilise this credit in financial year 2009-10 itself or it can carry it forward for utilisation in FY 2010-11

is there any time limt for availment and utilisation of service tax credit