I'll start my answer to this question by referring you to an earlier post in which I expound, in a mildly bossy fashion, about what I think authors should give away for free and what they should retain for Potential Future Book Publication.
Actually, most of my answer to your question is in that post, so please go and read it. I'll also say this: I can say 'do this, do that', a published novelist may say something else, a publisher may say something completely different. Ultimately the decision rests with you. You should do what you want to do. I'm also a big fan of working from instinct. If you *feel* you want to publish a chapter of your novel online, who am I to say that that feeling is wrong? We're all just guessing about what's going to happen - about what is happening. It's your novel and your intellectual property.