it's possible (not likely, but possible) that we could see a reveal as soon as tonight to coincide with the update - sakurai hasn't exactly been marching to the beat of nintendo's drum with these characters, after all. joker was shown off at the VGAs instead of a direct, piranha plant was a surprise drop in january, joker's feb direct appearance was just a token showing of 'yes he exists, please be patient', and his release in april just happened out of nowhere.
i wouldn't be surprised if erdrick just showed up out of nowhere in a mini-presentation detailing DQ content, VR and the new amiibo stuff dropping as soon as this evening, and they saved a more 'exciting' reveal for e3 itself. after all, we've been saying for months that erdrick seems a little too japan-centric for a western event.