Considering that the FY of your company ends on 31st March every year and it is not your first AGM:
AGM must be held by 30th Sept i.e. within the period of 6 months from the last day of the FY. (Refer Sec 210)
Provided that the time gap between the two AGM is not more than 15 months. (Refer Sec 166)
Minimum of 21 days notice has to be given before calling the AGM. So you have to ensure that the accounts are audited before sending the notice.
Since your accounts have been delayed, you may call the AGM even on shorter notice provided that the consent is accorded by all the members entitled to vote at the AGM.
It is possible in your case since it’s a Pvt. Ltd Company.
I would suggest that you show your AGM has been held without any extension. Ask your auditor to give the date that will serve your purpose and file the AR with late fees.
However you will not able to change the accounts signing date if you have already filed the Balance Sheet with ROC