The timestamp when the invoice is scheduled for processing, in RFC 3339 format.
After the invoice is published, Square processes the invoice on the specified date,
according to the delivery method and payment request settings.
If the field is not set, Square processes the invoice immediately after it is published.
Examples for January 25th, 2020 6:25:34pm Pacific Standard Time:
Pacific Standard Time with UTC offset: 2020-01-25T18:25:34-08:00