Be good to have invoice period box
I run a business where we rent equipment on a monthly or quarterly basis
so we run same invoices every month or quarter
ie 1 machine rental £0.00 invoice Period August 2018
then repeat invoice following month 1 machine rental £0.00 invoice Period September 2018
or quaterly Ie Invoice period: june july aug 2018 etc must be self populating on repeat invoices