You're at +6 right now, so the number of people (including me) who think that your comment was interesting and useful to the conversation outweigh the number of people who objected to it. HN is generally self-correcting; I would say that not asking about downvotes for at least two hours or until you get down to -4 or below is probably a good rule of thumb, as I expect that HN's tendency to self-correct is lessened past either of those points (because of fewer people reading the thread or because people won't bother reading the comment), assuming that you can't see why it's been downvoted. That's just my advice, though, as I most often see comments asking about downvotes following comments which have a positive votecount.