I can't think of a more perfect CastleVania game to start with than DXC; you're getting a remake AND a near-carbon copy of the most coveted CV game of all time, Rondo of Blood, and also an enhanced version of what is arguably the best metroid-style CV game, Symphony of the Night. Sure, DXC will be a hard game for a newcomer to the series, but I suggest playing through it long enough to at least unlock Symphony of the Night. Still, DXC is one of the easier classic CV titles (not as easy as, say, Super CastleVania IV, but easier than most classic CV titles, non-the-less).
All in all, you're making a fine entrance into the CastleVania series.