It sucks, but the best way to jumpstart a community is to regularly post into an empty void for a very long time, and let people slowly rely on the consistency and start talking once they have a schedule they can expect.
Which is ass, because you cant know how long that time is of seemingly posting shit for no one, to no one.
Yep, I saw this on the [email protected] community I mod. Posted something good myself every day for weeks and people start to pay attention, and now it's relatively active on its own with 2k subs.