When it tells me it’s done. Sometimes there’s still stuff in there that I’m not sure I’m happy with, but it’s already off and running around the yard and there’s not much I can do about it, other than learn to inhabit the song as a performer as best I know how. Once in a while I’ll reword a lyric, or something gets cut in the recording process when we realize it’s throwing the whole song off.
This answer doesn’t feel 100% truthful to me though, now that I’m reading it. Might have to have another pass at it next Q&A…