Depends on what you call "following".
If you mean followers on Youtube, Facebook, Insta etc. on social media, then it is just as Dave said above.
But even if you do not have that, I'd recommend you build a list subscribers of interested people who know about your future project and are potentially ready to back you right away when your campaign starts. That is something you can build "relatively" quickly (over a course of a few months, maybe even weeks). This is vital to catching media attention and drawing in new masses when your campaign launches.