Personally, I would never leave an 18-20 year old into medical school if I ever had the choice of making admission choices.
But what about all the countries where you go into med school straight out of high school?
I'm all for taking your time and doing things at your own pace. And for some people, that means speeding through. If I knew when I was 18 that I wanted to be a doctor, and I could get into med school at that age, I'd do it. Unfortunately, I didn't know until I was twenty and then I had to take pre-reqs and the MCAT.
I've "wasted" two years of my life. I repeated ninth grade when I came to the US (I started first grade when I was five so I was young for my grade, and the school I went to was 13 years instead of the US 12, so I figured repeating ninth grade in the US just kept me on schedule) and now I'm doing a year of work in between undergrad and med school. But I'm not upset about it, even though in retrospect I would have chosen differently.
Anyway, what I'm trying to say is, some people enjoy backpacking and trying different things, and some people just want to do one thing with themselves. Either way is okay, especially if you've at least considered the other way. I feel sorry for those who don't realize there are other options, but if they've considered the options and don't want them, it's okay. There's no right or wrong way to do things, just ways that result in fewer regrets.
To the OP, I say apply if you really, really feel you're ready to start medical school, enough that you're willing to prove that your age is not a concern and you're willing to accept that you might not be given proper consideration because of your young age. However, if you are open to the idea of waiting, wait, and try some more things, do some new ECs, before applying.