+1. I think the best strategy is to be flexible and adapt as the active community on Discourse grows.
I used to spend more time moderating forums years ago. My observation was it is better to start a new community with broad categories before a community has built up. People have different motivations for using the site, and broad categories gave more flexibility for a wide range in topics (without something getting buried in a sub-category not everyone read or checked often).
Once there were better patterns of popular topics in a category, we broke them off into a smaller sub-categories. We also moved old posts into the new sub-categories to make a dedicated space around a popular topic within our community.