-In normal cases, the bill book should be issued on or before the date of delivery.
--For a continuous supply of good, you must issue the bill book on or before the date of issue of the account statement
-When it comes to services in the general case, the bill book should be issued within 30 days of the supply of services
-If it is through bank and NBFCs, you should issue the bill book GST within 45 days of supply of services.