To quickly create invoice for a number of jobs, simply select necessary jobs using Shift (to select range of jobs) and Ctrl (to select jobs one by one) keys.
Click Create invoice on the ribbon. To create in-advance invoice, click drop-down button and select In-advance invoice.
If you selected jobs for different customers or with different currencies, than you will get a notification that invoice can not be created. In other case, invoice adding form will be opened, where it will be possible to make final changes before saving new invoice.