Once you've got the first novel done, then for subsequent WiPs it probably will help to give trusted readers a few chapters at a time as you've written them. That's what I've been doing for the past few years and it's worked very well.
However, if you're new to writing, I'd recommend that you write the whole thing then leave it for a time while you write something else, then come back and revise it, and only then worry about someone else reading it. I fully understand that you don't want to write drivel, and it might seem to be a waste of time and energy to write 100,000 words or more and then decide -- or be told -- it isn't working. But it really isn't a waste. It's important to learn one's craft, and the way to do that is to practice, so even if that first draft isn't very good -- and the first draft of most people's first book isn't -- you'll still be learning from it.
Having a critique for the first time can be really hard. I suspect that every single writer here has felt at least a tiny bit crushed no matter how kind and gentle that critique was. It's all too easy to hear "This needs a bit of work" as "This isn't good enough" and then "You're not good enough". That's dispiriting however much experience one has, and for someone who has only just started writing it might be enough to shatter confidence entirely and bring the whole project to a sudden halt. If, however, there's the novel already written, the writer knows he/she can do it, so there's more confidence there which (with luck) will be enough to sustain however much revising is required.
There's also the risk, if you're getting advice on a chapter by chapter basis, that you keep revising those chapters to get them right instead of actually ploughing through and getting the first book written. Plus, if the person critiquing has more writing experience, he/she might start taking the lead in suggesting how the story should go, warping your own vision of it.
If you're very, very sure you won't be distressed and deflected by criticism, and you're confident in your abilities and your story, then as TBP says, put up a few hundred words of your opening here in Critiques when you get your 30 counted posts. That will at least tell you if you're heading in the right direction.
Meanwhile, this is very much a writing issue, so I'll move it to Writing Discussion.