I agree with what everyone has said, it can vary from person to person.

With my first daughter I showed by the time I was 12 weeks and bought loose pants, but the weight gain wasn't too bad. With my second daughter, man, I put on so much weight and was in maternity clothes easily by 14 weeks!

With this pg, it's so the opposite, I've put on 4kg and I've only just decided that wearing my tiny jeans are uncomfortable and I'm into my bigger sized jeans. My stomach has only just started to pop out now. So each pregnancy varies too. I thought I'd look about 8 months pg by now, cos I've already had 2 children, but I had some one ask me last week "Oh, are you pregnant?" So it's different from person to person and with each pregnancy too.