For real, or when you should make the first and second commit.
Or worse, when you're too focused and start making a ton of changes, then you realize you haven't committed anything. Discovering I can stage ranges has made me fall for this way too many times, because I think I'll easily just go back and extract one atomic change at a time later (spoiler: it won't be easy ( ; ´ Д `))

as soon as you realize you can't easily contain your commit message within a 50-character conventional message (or slightly more if you wand to be more specific about the scope)