Hi Praveen,
what i did was i created a new order type, standard order, created a delivery block reason in Logistics execution, assigned this to the new sales order type, I created an order related proforma invoice and a standard delivery based invoice document, performed all copy Controls from sales document to biling, delivery to billing, I used standard item categories, assigned it to the new sales order type, so the process worked like this
Create sales order in VA01 with automatic delivery block on header level
Create a proforma invoice sent to the customer for payment
When payment received, create a booking in finance ( no accouting document at this stage)
Release delivery block and confirm quantities in Schedule lines
Create delivery, pick/pack goods issue
create real invoice to customer with a text for information purposes only
Accounting document created and finance clears the customer payment
This worked and the business were happy with this solution