How to create task from sales order and invoice based on timesheet?

In project management, a task is an activity that needs to be accomplished within a defined period of time. For a company selling services, the task typically represents the service that has been sold to the customer and that needs to be delivered. This is why it is useful to be able to generate a task from a sale order in order to streamline the process between the Sales and Services departments.

As an example, you may sell a pack of 5 Days of Consulting Service at $120 / Day. The price is fixed and charged initially. But you want to keep track of the support service you did for the customer. On the sale order, the service will trigger the creation of a task from which the consultant will record timesheets and, if needed, reinvoice the client according to the overtime spent on the project.