And btw, from what I have see so far YC seems to be a great place to launch. You get lots of early adopters who don't mind seeing a few broken links and are willing to give very pertinent feedback.
-Launch when your app is at a stage where it is usable with a minimal set of features then iterate on that 1st version based on your ideas and feedback from users
-On one hand: if you launch something too crude, no one will come back after their initial visit
-On the other hand: the more you wait until launching, the more you risk loosing on your investment.
-Imagine pouring money in a stock without ever seeing its performance/chart. That's what not having feedback would be like.