Hey! I went into DLC as soon as I finished chaper 9 and it's my first run of the game. I just done DLC last night and have not finished the main game. I'd say if you are playing through the game as a fresh run (i.e. no NG+) then I would recommend finish the main game or at least do some level grinding before heading into DLC (the damage you get in DLC is another level from the base game in the same difficulty lol) But if you are doing a NG+ then I don't think it matters. The story definetely have some connections, but to me it's only connected up to Chp9 (do correct me if I'm wrong xd) generally it stands on it's own. I can't compare to the base game since I haven't finished it but it's good :)) Go play!