The two big reasons to read Chosen and the Beautiful first are that it explains what's going on with the paper magic and that it reminds you about what happened in The Great Gatsby (if, like me, you read it as a high school assignment and retain only a few striking images and phrases). If you know the underlying novel better and are willing to roll with worldbuilding, I think you could go in either order? Chosen and the Beautiful is novel-length, so it's a question of whether you'd rather treat the novella as an aperitif or as dessert.