If you are the entrepreneurial type (like to run your own business), you could get started in just a couple years with modest equipment, even the JD in your avatar would be a start. IF you really want to make good money in life doing work with 'heavy equipment' you need to own the company. Start small, be a good businessman, and don't use debt to build the company and you'll be well on your way to success.
I started my first business when I was 17 using rented and family equipment, working after school/weekends/summers to build up the business, add equipment, etc. I got a Bachelors degree in Agricultural Economics, then got my contractors license and now build barns, fences, and do plenty of light grading/excavating. I have modest equipment but make a good living by finding the right niche. I enjoy running the big yellow iron and rent dozers, excavators, etc when my jobs call for it, but I don't really strive to be just a grading/excavating contractor. I've found the best money to be made with machines isn't by doing hourly work with them, but instead using them to complete a project you bid on. (although hourly work is a good start)
Also, one of my cousins started a landscaping company when he was 15 or 16. It took off and he was owning trucks and equipment before he even had his license. Had employees that drove the trucks and helped with the work. It's all about working hard, being smart with your money, and being honest and personable.
With all that said, if you are not the business owner type that's ok (in fact there are a lot of people that own businesses that shouldn't). I also know people that are quite content just running the equipment and getting paid for it. For some it's just a side job because they like to do it, for others it's their full-time living. Regardless, you can't go wrong by doing well in school, getting a good degree in business or whatever and pick up the skills/trade licenses on the side along the way.