does anyone know where Paradox fits in on the time line?

You've read Paradox already right? So I don't need to explain the events of Paradox.

Basically, if Akise were to obtain a diary the world would have come to a "good" end (which basically happened in Paradox).

Think about those Shounen manga in which the main character saves other characters from an "inescapable and predestined fate" (AHEM, Naruto... -_-). Akise basically saved all of the other diary holders that Yuuki ended up killing in his storyline.

However, Deus's assistant altered and reverted the reality of the world and turned it into what you're currently reading in Mirai Nikki.

So basically, Paradox is a prequel. (I think? o_O)