PR creation for Sales Order not for Sales Qoutation

Hi,

Can you help on how to set up the system on below mentioned scenario

Client Requirement :

Purchase Requisition(PR) must be created against those Sales Orders whose Sales Quotation are approved by customer(in other words - Sales Quotation which were accepted by end customer).

No PR must be generated for any sales quotation.

Can you help on how to achieve this & what config needs to done.

Thanks - Dave