Originally Posted by BatLobsterRises
Don't forget though, she approached him holding the mask to her face, but he still recognized her.
Also, Lucius tells Bruce Miranda is lovely after the ball scene, and he has the same annoyed reaction as when Alfred tells him prior.
I would guess that Bruce and Miranda have at least been in the same room before (the Wayne board) even if they haven't had a personal one on one convo until the charity ball scene.
Granted the novel is not the bible but IIRC, it was mentioned there that the ball was their first meeting. I think there was some blurb about Bruce thinking that "Alfred was right after all" when he said that Tate was lovely after he saw her at the ball. To me, more signs point to the ball being their first face to face meeting (which is quite odd given the circumstances (like her being one of the funders for the clean energy project and Bruce apparently knee deep working on it in the first 5 years) but whatever