This widget shows amount of jobs, which are delivered and ready to be invoiced:
You can specify invoicing threshold for each customer. Until amount of delivered job isn't be reached, this customer won't appear in this list. By default, this value is set to 1. Setting it to zero fully excludes that customer from this widget.
To create an invoice, double click on any card inside this widget. A new invoice will be automatically created and filled with the data of uninvoiced jobs. Payment term will also be automatically detected using settings you specify for a customer.