Personally I think you can "Show HN" as long as there is something to see and it's not a waitlist. (I can't speak for anybody else but I will probably flag you if you post a waitlist.)

It's also fair to have a corporate blog where you write about your product, your story, your interest, what you ate for breakfast, anything. Just, if you are posting stuff from your own blog and nothing but stuff from your own blog you will find your post start out [dead]. Don't make that rookie mistake! If you post from many different sources there is no problem with occasional self promotion.

There is a "showdead" flag on your profile which you can flip on which will give you better visibility into how moderation works.

Also note that if you post something it might just drop like a rock and get no attention. Happens sometimes, in fact, most of the time (go look a few pages past "new" and see how many things get > 5 votes) That's why the blog is a good idea, if one post doesn't connect with people you can write a better post.