Pls find Rule 48
(4) The invoice shall be prepared by such class of registered persons as may be notified by the Government, on the recommendations of the Council, by including such particulars contained in FORM GST INV-01 after obtaining an Invoice Reference Number by uploading information contained therein on the Common Goods and Services Tax Electronic Portal in such manner and subject to such conditions and restrictions as may be specified in the notification.
Provided that the Commissioner may, on the recommendations of the Council, by notification, exempt a person or a class of registered persons from issuance of invoice under this sub-rule for a specified period, subject to such conditions and restrictions as may be specified in the said notification.
(5) Every invoice issued by a person to whom sub-rule (4) applies in any manner other than the manner specified in the said sub-rule shall not be treated as an invoice.
Therefore, only when the e-invoice is generated, it shall be considered as invoice. Appropriate tax period in your case is Oct 2023.