When an event has not been published, it is considered a draft. While in draft state, notifications for the event will not be active. This means that your attendees will not receive notifications from your event until you publish it. The only people who can see your event while it is in draft state are the organizers that you have assigned to the event.
You can create scheduled notifications while your event is in a draft state but the notifications will not be sent unless the event is published.