Enabling Reminders - Does it mass send?

If I were to enable the reminders in v4, does it bulk send emails out to everyone that meets the criteria at that time? Or will it only send to people who hit that criteria moving forward?

From what I’ve seen in the past working with v4 the reminders only hit the “moment in time” moving forward.
So if you set up the reminder cron job today, it will only send reminders for invoices hitting the reminder date from now on. Past (overdue) invoices which are already over the reminder time will not receive a reminder mail.