To setup Payment before fulfillment in Order to Cash Process, enable the feature Invoice in Advance of Fulfillment
To enable the feature,
Navigate to Setup > Accounting > Accounting Preferences.,
Under the Order Management tab, in the Invoicing section, check the Invoice in Advance of Fulfillment box.
After we enable this feature, when we create a sales order, after approving, it will navigate to a page where there will be option to “bill” or “fulfill” . If we click on “bill” we can invoice the same. Please check the shared image below:
Thank You!!