Source
It looks like that picture from the article is from episode 3, because there's pictures of AJ, Paget and Kirsten from behind the scenes of episode 3 and Kirsten is wearing the same dress.
Picture 1
Picture 2
I shared the links of the image addresses because you can zoom in and read the article better and see the picture better. It's kind of small from tumblr but if I enlarged it, it was too big on here