You're not expected to wait around for the opportune time to demon dodge, especially since the AI in DmC reacts to the player, so the more aggressive and combo heavy you play, the more likely y0u will find yourself doing demon and angel dodges in the midst of fast paced combat. The way you're describing dodge is exactly what made dodging so clunky in the older games, it required too much set up (must be locked on, must input direction, must deal with positioning based on the direction you locked on, etc) and focus to properly dodge during combat unless the player was using trickster. In DmC, you have the same kind of flexibility as trickster, but instead of only during that style it is all the time. The dodging is more lenient, because its expected to be part of combat, you're supposed to demon dodge and angel dodge with high frequency, because the mechanic itself is look stylish. I mean I never can get over how awesome Dante looks when he demon dodges successfully in the air; its beautiful and its icing that on top that you can combine it with angel dodge to dodge back into place to deliver the hurt on demons.
If you haven't seen my hunter video, check it out, notice how you get more chances to demon dodge and angel dodge as you play more aggressively, if you wait around for the enemies to attack and just dodge, they won't attack you with the same level of frequency and aggression.