I don't have any direct experiences with it, but I know people who do. There are many doctors who believe that it's at least partially due to the extra hormones we get in our meat and dairy products. They recommend organic meat and dairy products. (If not completely organic, meat and dairy products from animals that weren't given any steroids is okay. Organic includes that plus the fact that they're fed organic grass and grains, but that's not thought to be a factor for precocious puberty.)
When caught early, some people are able to reverse the symptoms by switching to organic products. For example, if it's a girl whose only symptom is breast swelling, it may be possible to reverse it. If it's progressed to the point that there's been hair growth in places that only adults have hair or if cycles have started, it's much less likely that the symptoms will reverse.