I agree with suzeeq. If there is one thing you can be sure kids will do, it's grow. Another tip I got on these forums is to measure a garment that fits as desired (such as another sweater or a sweatshirt) and use that measurement in determining the size you should make. I'd pick a garment that would fit the torso about the same as the sweater in the pattern. Its a darling sweater, bet it's for a darling girl.