I have posted a blog post[0] explaining I was building a redundant storage service for developers. It was on the front page for about 4 hours. I think the best place it got was about 18th. I didn't put analytics and wasn't very careful about my logs. Actually the logs report the same IP all the time: the HTTP proxy and no referrer URL :)
I got very few people who sign up (which amount to choose a login and a password, no email required), I think it was around 10. Only one person tried really the service (i.e. uploaded an SSH public key and uploaded a few files).
The interesting thing is that even when the post had slipped from the front page, it was still generating a bit of traffic, possibly doubling the number of person registering.
The best thing I got from that post though was some feedback on HN itself but also a couple of persons sent me an encouraging emails. For that reason alone, even if you're not ready (you never are), post publicly your work as soon as possible.