So obviously, this is taking place before Castlevania, Simon's Quest, and Dracula's Curse, but what about Lords of Shadow? Seeing as Gabriel is Dracula, and from what we've seen, Gabriel is still the main character in Lords of Shadow 2, when could Mirror of Fate possibly be taking place? After Lords of Shadow but before Lords of Shadow 2?
What everyone above said. This is actually in a totally different timeline. Although certain characters have the same names (Alucard, Simon, Trevor, the surname "Belmont" in general, etc), the backstories for the characters themselves are completely different, and the canon in the original series isn't reconcilable with the canon of the LoS series.