As the GSTR 2 has not been started , so can claim ITC on the original bill you are having. But has to refer the 2a also as in Annual return the ITC will autopopulated from 2a. So in short If any bill which is not with you but reflecting in 2a it has to book in accounts , you can ask for the copy of same from supplier & the bills you are having but not reflecting in 2a then ask your supplier about it .