Subscribing to small (previously unseen by kbin) communities

How does this work on kbin at the moment?

My understanding is that, at least on Lemmy, you should be able to search for a full community name, wait a while, and have it show up and start federating. I've been searching for two communities (in the format name@instance.tld) on kbin since yesterday and it still shows no matches.

Both are small (<20 subscribers) and currently inactive (no new posts in a week). Do I need to wait until there is new content in them?