I think we need a Slack channel ASAP to form and organize a community
We have a slack for the core team.
I believe that organizing the community on here is a better solution because people who are just strolling by can see that there is activity. Also people who don't want to join a slack channel have the opportunity to see what is going on and participate.
With a slack we can organize better than here in a forum post I assure you, and it's more convenient for people who really will help out. You can always post here major announcements regardless you have a slack or not.
Ultimately the decision is yours, but I think you should consider it.