While you're publishing, if you don't want to post you LIVE immediately on Facebook, you can set a Date and Time of when we have to publish on behalf of you.
When you decide to schedule, you can also decide to send immediately a notification to all your users about your upcoming LIVE event, simply use the On OFF "Notification" button. This is a powerful tool create by Facebook, that will send a notification to all your users saying "The Page xxxxx has scheduled a LIVE for yyyy" where "yyyy" is the time when you'll go LIVE. Clicking on that notification, you users will be able to receive a reminder a few minutes before that LIVE will start, making sure all your fans will be reached by your next publication.
This feature is available only for automatic publishing procedure.