I started to gain control at age 17, but I did it by sharply increasing the rate at which I injured myself. It wasn't until about age 22 or so that I actually learned to prevent meltdowns without having to resort to extreme (and temporary) measures. I believe it would have happened much earlier had I known I was autistic before the age of 19, when I was diagnosed. (My mother knew when I was 11 but did not believe it was a problem because I can talk and take care of myself, so she didn't consult a doctor.)
I cope with overload daily. That is and always will be a part of my life. However, most of the time I can prevent the problem from escalating by using different strategies for sensory, social, emotional, change, and transition stress.
This has led to a rather unconventional lifestyle. I am a loner with very little social contact; I spend most of my free time in intellectual or recreational activity. I allow myself to do "strange" things in public, like stimming or wearing a blanket-like cloak. I have routines for most parts of my life. Every other week, I go to counseling for advice on solving problems; every month, to trade ideas with other autistics in a support group. I wear no make-up, cut my hair very short, and choose my clothes for feel, not style. (If I have ever been in style at all in my life, it was accidental.) I am lucky to not need much social contact; but I do go to church, which fills the dual roles of giving me spiritual support and allowing me to socialize so that I don't lose the skills I have.
This might seem like a lot of bother, but one must consider that during my teen years, I had all-out temper-tantrum-style meltdowns two to three times a week. During those years, I didn't know I was autistic, and the whole sensory world annoyed me. I didn't realize how bad polyester made me feel. I had to constantly socialize with parents, one of whom was abusive when he was home (which thankfully wasn't often; he was usually at the casinos). Worst of all, I didn't know why I had those meltdowns; so I blamed myself for being immature and uncontrolled.
Today, I don't have all-out temper tantrums anymore. I have destroyed objects (Jenny McCarthy's book was the last victim... it was a library book and I had to pay $27); I've cried; but I haven't been completely out of control in years. There has always been enough left to find a private place, retreat, and calm down.
I worry sometimes that I will have a full meltdown in public someday and end up in the hospital, in jail, or worse... At least I am female, short, and fat, and do not seem threatening to most people.