Delivery challan vs way bill

Sec. 2(32) of CGST Act, defines “continuous supply of goods”

(32) “continuous supply of goods” means a supply of goods which is provided, or agreed to be provided, continuously or on recurrent basis, under a contract, whether or not by means of a wire, cable, pipeline or other conduit, and for which the supplier invoices the recipient on a regular or periodic basis and includes supply of such goods as the Government may, subject to such conditions, as it may, by notification, specify;

-> Only regular supply and delayed billing for no reason will not make it a CSOG.

-> Supply of gas via pipeline can be a very good example in this case. Though gas has been supplied continuously but the supplier cannot bill at the same time because the usage is not known. He will bill at the month end (can be other period as well) after considering the usage. So, this justifies delayed billing as well and will be considered as CSOG.

So, in your case, if delayed billing is justified, then you can do what is being said by you.