Ask HN: How to promote a minimum viable product?

I spent the last few weeks in an emotional rollercoaster building a webservice. I finally got a minimal product working, but I'm way too biased to recognize if the product is valuable or on the wrong way. With zero users, my product desperately cries for some early feedback. On the other hand I feel insecure about releasing an unfinished product which may contains bugs and with just one core feature to an public audience. How do you promote a MVP, and how do you decide when it's time for a first release?