Same concept as calendar invites, however, not everyone uses their iCal or Google Calendars. Use a Facebook event to remind people when your campaign is going live.

You can also post updates and engage with your followers leading up to the date via the Facebook event page.

I'm going to keep repeating this (it's that important): You want to set up as many asks/touches/channels as possible, so don't be afraid to double-down on reminders.