In my business, there are certain stages for each sales process:

1- Estimate Generation

2- Acceptance of Estimate

3- Create Sales Order and keep track 

4- Follow up Deliveries...shipments, and generate packing list to be attached

5- Then... send invoice to customer

QBO support team:
- Accepting Estimates is not Order, so please  work on it!

- printing packing list is not possible without invoice creation, but this is not always desired.

Thanks

Wajdy