After the fourth book.
I mean, I saw a bunch of H/Hr moments in that book too, but Ron’s reactions (yeah, Ron’s reactions and not Hermione’s reactions) made me think that in the end JKR would put R/Hr together.
Of course that in the fifth book I still had hope… but then the sixth book was a mess. Sometimes I didn’t recognize any of my favorite characters in that book. Especially Hermione. Then I was sure that the end would be R/Hr.
But even so, I didn’t change my mind. I’ll be H/Hr forever. :D