My opinion is, As per Sec 16 (4)
A registered person shall not be entitled to take input tax credit in respect of any
invoice or debit note for supply of goods or services or both after the due date of
furnishing of the return under section 39 for the month of September following the
end of financial year to which such invoice or invoice relating to such debit note
pertains or furnishing of the relevant annual return, whichever is earlier.
If You paid totally to your vendor with in 180 days for said invoice against your receipt of goods / services, as well the ITC reflected in your GSTR 2A, you can avail input before filing September 2020 return or before filing GSTR 9 for 19-20 whichever is earlier.