For availing ITC there are four conditions, two of them being:
1. You are in possession of the invoice,
2. You have received the goods.
One of the other two condition is irrelevant as it says you have to file your GSTR-3B which is very obvious.
And the last condition says that supplier must have paid the amount of GST to Government which is quite vague as no procedure is prescribed for such checking.
Additionally, the GST Rules say that you can take ITC once the same is reflecting in your GSTR-2B.
Hence, these three things have to be looked into:
1. You have the invoice in possession,
2. You have received the goods, and
3. Invoice is appearing in GSTR-2B.
Further, the ITC pertaining to a Financial Year can be taken till the date of filing of GSTR-3B for the month of September following the next year