to build a community for syndicate, i'd first identify who really needs the product. from region to type of people and others.
I won't try to get everyone in so fast because if i'm inviting everyone, then i'm probably inviting no one; I'll carefully select few people,even if it's by sending them a dm to check Syndicate out, then we can build a community from there — not necessarily thousands or even hundred people on the first day.
after that i'd ask myself why they should stay. people join communities every day and mute them after a few minutes. there has to be something they keep coming back for.
and before all that, i'd spend some time putting useful stuff out there. if people already know me for something, getting them into a community becomes way easier.
I really don't want to mention what I read from the doc. although I already have an idea on some of them before, plus I'm still learning, so I'm sorry if I didn't really sound buoyant enough while answering this