ITC for tax paid under RCM

I have to pay GST under RCM for rent paid to unregistered dealer. This payment has been included in GSTR3B fr March month. In which month's GSTR 3B should I claim Input tax credit for this GST paid. When I am putting it in 3B of March itself, it shows us a warning that ITC is more than that appearing in 2B (even though we have paid this tax in cash). Should we ignore the warning and proceed with filing or claim it in the next month i.e April (Will it appear in 2B of April).