payment page do not show when checkout - but show only after confirmation by manager

HELLO i have such situation:

all products in shop are not in stock on the storehouse , and i have a lot of suppliers of this products. So i do not need that the client in checkout pay for his order. I need that the payment page was available only after confirmation by the manager of the shop and after the change of the status of the clients order.

How can i provide this in my shop?