Don’t be afraid that nobody will join your community. Assume that’s what will happen. Assume you have 0 members when you launch. Reaching 100 members in two days is a far-fetched dream.
Instead, focus on all the hard work you need to put in to get people to join. Focus on the relationships you need to build. Focus on persuading one person at a time. Be single-minded in your approach and build from there.
Hopefully that fear will fade and be replaced by the determination to do the work required (or not attempting to build a community in the first place).