How Can i train my green horse for barrels?

Well, im most definitely a good rider. I show quarter horse level pleasure classes have the top trainer in my county. i have gotten numerous awards. Im 13 years old and almost a finished rider... I can handle any kind of horse. I have a 10 year old green gelding has a 3 time world pedigree but in western pleasure. BUT hes built more like a event horse has the hocks, muscle, perfect conformation for barrels, poles, cutting, etc. He needs alot of work, hasnt been ridden and worked in a while. so i want to know how to start him i was thinking about lunging for the 1st week. then walk him through the pattern for 2 weeks, trot him for 4, and then lope him and when hes ready let him go. how am i going to get him turning good? im only 4'9 im really tiny and hes sooooo powerful also the bit im starting him with is a o'ring snaffel does anyone have tips on how to start him differently? This horse can make it to the top if i train him right...