It would be helpful if invoices could be generated and sent on a specified date and time (i.e., send by email but delay until date and time determined by sender). At present, invoices are sent manually the day of the appointment. If admin could generate an invoice the day before and delay an automatic send until the next morning (of a scheduled appointment), it would save admin some time and clients scrambling to find invoices to pay immediately prior to their consultation. Note: some invoices via email are not delivered until after scheduled appointments.