貴方はそれを終えましたか。それどこか、今始めたところです。
anata wa sore wo oemashitaka? sore dokoka, ima hajimeta tokoro desu.
Have you finished it? On the contrary, I've just begun.
But I've never seen that usage before - 'doko ka' to mean 'on the contrary'. Is it common? Or is it a mistake?