From: Modern Racer - Launch Techniques

In general, automatic transmissions are known as being more useful for lazy commuters than for hardcore racers. But it may be surprising for some to know that many pro drag-racing cars have heavy-duty auto gearboxes. That's because the brake-torque launch is an automatic specialty. This launch involves keeping the car stationary by flooring the brakes with the left foot, while using the right foot to rev up the engine against the torque converter. In technical terms, this preloads the entire drivetrain with the stress of a launch, allowing the engine to rev closer to its power and torque peaks at the starting line. Brake-torquing is also beneficial for turbocharged engines as it allows boost to build up before the launch, reducing turbo lag. The only problem is that there is a lot of stress on the transmission, and the consequent heat build-up can destroy your automatic gearbox. Unless your car has too much power for the tires to handle, a brake-torque launch usually will not spin the wheels. This is because the automatic transmission absorbs the shock by design, and brake-torquing actually reduces stress on the rest of the drivetrain. Instead of a sudden massive load, the drivetrain has the torque applied slower instead of one huge jolt.

If you're at the track for the first time and if you're trying to simply establish the baseline performance of your vehicle, forget about trying to cut a good light. It's simply too much for most beginners to work on both their reaction time and launch techniques at the same time, so don't be afraid to leave a second or so after the green light comes on. Your reaction time will suck, but the reaction time is not factored into the elapsed time. Only once the car can be launched perfectly each time and every time should one start worrying about cutting good lights (or beating the guy in the other lane, for that matter).