Of course there are her prophecies in Himatsubushi-hen (Time Killing Arc), I can't remember anything before that, but there's no guarantee. I'd have to read them once more to be sure.
There is a strong hint in Atonement Arc, volume 3, starting from page 104, when Rika meets Rena in her hideout and tells her mysteriously about "this Rena Ryugu" and "the next Rena Ryugu". This was shown later in the anime, at the beginning of the second season.
The name Hanyu appears already in Meakashi-hen (Eye Opening Arc), when Rika