Barely bump in, then learn the reaction time of the car. Most people leave on the start of the last yellow light. Some cars that are a little lazy, get a 1 count on the second last yellow light and go... Have to practice to what works for your car, but you take advantage of that roll out distance to get a running head start before the timer ever starts. If your all the way to the other side of the roll out, your reaction time trips the timmer sooner, but the car is doing 1mph versus 5 or 10 when the timming system starts "counting" the pass.
Same reason there are/were staging wars. When you stop the car, even the momentum from as slow a motion as staging, when the staging triggerd the tree, the last car to stage had forward energy still that hadn't dissipated,, so as he/she mashed the gas, it was a little more than the other guy had, that had dissipated that energy at a dead stop.