GST Amendment invoices in portal doubt

The Amendment option in GSTR-1 can be used to make changes or modifications to the information that was furnished in the original GSTR-1 return. This option can be used in the following cases:

• Correction of errors: If any errors or mistakes were made in the original return, they can be corrected using the amendment option.
• Omission of invoices: If any invoices were left out of the original return, they can be added using the amendment option.
• Changes in details: If there are any changes in the details of the invoices such as the name of the recipient, invoice amount, GSTIN, etc., they can be updated using the amendment option.

Its better if you can amend the same before filing your Mar 23 return.

Or 

You can amend before filing Sep 23 returns as per the govt. notifications.

There is no issue if invoices missed out it can be included.

Oct 23 - For monthly returns

Sep 23 - For quarterly returns