That graph is a bit, um, wrong, really. You should be carrying slight brake pressure past the turn-in point, this is called trail-braking. Cars can slow down and turn at the same time (slightly). Make sure you roll on the gas nice and smooth as you "unwind" the steering. The string theory is a good one. A string is tied from your wheel to your gas pedal. The more you press the gas, the more you have to unwind the wheel. The apex of the corner or "clipping point" should be your cue to start adding power.
The time when you're off the brake/gas should really only last as long as it takes to get from one pedal to another. If you can't add power right then, just hold "neutral throttle" (just enough to maintain speed) after you come off the trail-braking.