The kid just moved to Salem. When you see his house, in various shots of the movie, all the rooms are filled wiht boxes, except HIS room. It is completly unpacked. He must be pretty fast at unpacking.
It's pretty hard to unpack an entire house, you know. (Believe me, I've moved a few times before.) He just didn't have as much stuff as the rest of his family. What do you think would be faster, unpacking the boxes of one child, or unpacking the boxes of an entire family?