I had @csallen on my podcast called the C2C Podcast (C2C = Customer to Customer) where we have community builders break down the strategies they used to build C2C communities.
The TL;DR is he validated before building with opt in pages instead of fully built features then made conversations with himself to kickstart the community until it was active on its own.
My key takeaways were:
Validate from elsewhere: See if there are other products similar to yours that people are paying for and have a growing customer base.
Gauge interest then build: Instead of building the forum first Courtland had people subscribe to join which validated it.
Getting Traction: Starting off it was a ton of cold outreach for interviews and taking blog-worthy content and making having conversations essientially with himself as a way to show the content in a forum format. Then promote it to the newsletter to get others to contribute.
Activating in-person meetups: IndieHacker meetups have taken a life of its own! If you give your customers the opportunity to host meetups and help promote them you might be surprised what happens.
Let me know what you think! https://www.bevylabs.com/pod/18/
#meta