Credit Check at Invoice Level

Hi, Now system will check the Credit limits at the time of Order Booking, But we need to changed this process. While Book the sales order the system should not consider the Credit Limit up to Shipment process, after Complete the shipment the system do not generate the invoice in AR, The Invoice should generate after make the Receipts or Credit Limit for the customer.

Please help us to complete this process.

Thanks

Mohan