Yes, go teach. You don't have to be an expert about it. No one ever is. You just pick up more as you go along.
You'll make some money (although not much because it will extra time at first to figure out what to do). You get some experience, see if you like teaching. And if the parent is willing (dumb enough) to pay someone with no experience to teach their kid, they get what they get. Most likely the parent will be trying to give their kid a taste of music and see if they're a great prodigy... Or just to give a taste and be able to say their kid took piano lessons. With the number that quit after a few lessons, a few years, or that most people stop playing after high school I wouldn't worry too much about messing people up.
So yes, teach. What do you really have to lose? The worst case scenario is that you scar someone for life and they don't become what they might have on the piano, but that's fairly unlikely I would think.