Invoice numeration is sequential and begins from the value specified in “Next invoice number” field of “Documents” section of plugin settings dashboard.
The value specified in the image automatically increases and shows next invoice number that will be generated.
If you change the value and save new settings, the first new invoice will no longer follow previous numeration, but it will begin from the new specified value.
You can add a prefix and/or a suffix to invoice number by changing invoice name format in“Invoice number format” field.
Enable “Reset on 1st January” field if you want to rest numeration and to restart its cycle at the beginning of the new calendar year.