You can limit the invoicing open item selection only to open items with a next invoice date prior or equal to the specified date.
By default, this date is initialized to the current date.
The selected scheduled invoices are also filtered according to the entered Invoice date: only the scheduled invoices whose next invoice date is prior to the entered Invoice date are considered.
For example:
Invoice date: 05/10/2019
Scheduled invoices until: 05/15/2019