That’ll work when typing things online, but not in f2f conversations. I thought about ‘com(m)’ which will work, typed out in certain contexts, but I think that sounds too much like other words in several languages including English to use in speech. But if you prepend ‘lemmy’ to that it’s quite a distinguishable word that sounds like ‘lexicon’: lemmycom(m)!

There’s a lemmycom for that.

“Community” as the other replies already mentioned, but how do we abbreviate that? “Sub” worked well imho, but does “com” have the same ring to it? Any better suggestions?

I’m not familiar with the details of setting up a Lemmy instance, but can’t you already get the new instance up and running with a modified /etc/hosts instead of waiting for the DNS to be updated? That might reduce your overall downtime a bit.