That will only work when you create a quotation / sales order.

If you want it to happen when you confirm the sales order, you can trigger it on creation and update and add domains (and a trigger, but that's not required).  

There are two domains:

1. Before Update Domain (used for Updates only)
2. Apply on

In your case, "before" is status is NOT Sales Order, "apply on" will be that status is Sales Order.

https://odootricks.tips/automated-actions/