You can get Paine's special dressphere in chapter 1 and in the chapter you need it! Just go to Macalania to Trommell and talk to him 3 of 4 times and Yuna will tell she's a sphere hunter and he will give you the sphere!!

Good luck

We already have plenty of threads talking about Special dresspheres and how to get Paine's, so I'm gonna close this one.