Who will post it online before you if it's never been posted online before? Do you often have people peering through the window copying what you write?
I can easily tell if someone has duplicated their content somewhere else. We'll just have to play it by ear. The actual window between posting and payment can be shortened. (this is kind of new so it'll probably need refining) we'll just have to work on trust, besides anyone that copies stuff is breaking the law. If its a blogger blog a quick message to google or an email to their host will have it sorted out.