Assistance in both places would be great. It’s possible to launch a new Discourse site without having any idea of what custom groups are intended to be used for. Configuring groups in the Setup Wizard would make that clear:
I’d take the idea a bit further and deal with specific use cases for groups in the Wizard: Why isn't Discourse more frequently recommended as a "community platform"? - #131 by simon, but just allowing groups to be configured in the Wizard would be an improvement.
For context, I’ve answered a zillion support questions about Discourse custom groups. It’s not a concept that’s well understood by new site owners.