When you create an invoice in Informer and send it at a later time, the invoice will be dated according to the date of sending. This is usually not a problem, but sometimes you may want to keep the date you originally specified: the concept date.
If you want to keep the specified date, you need to activate the toggle 'Post invoices on draft date' in the sales settings.
Once this setting is activated, the specified date will be maintained when the invoice is sent.