sampow, I was just about to reply to your post. So I'll do it this way.
The lightning itself is a clue.
EP1: Josy flashes herself.
EP4: Josy is actually behind the camera and is not flashed.
EP9: Josy is not used to being in front of the camera because the flash surprised her.
Now you just have to read what Josy says just before her flash in EP9.
View attachment 2685691
Oops.
"It’s not illegal for
friends to be in the same picture."
Friends is definitely a DPC clue that leads us to EP4 because that's when Josy and Maya took a picture before they had sex for the first time, and Josy was behind the camera. Why is this important?
Maya said in EP4 flashback that Josy, who wanted to move in with her father, has friends here too. I figure so she had more than friends. So who is the one who knows about cameras and also sets up the camera in EP9? Elena.