hell no, 27's not bad at all....if this is what you want to do, then i say go for it! too many people are doing jobs they no longer want to do and even i'm one of them that wants to switch from what i'm doing (only i don't want to be a pilot). I've seen pilots start their time building career at a much older age than you and succeed
so take that with a grain of salt because it's all about your determination and how badly you want this!
i wish i would have decided i needed a career change at 27... i'm now 10 years older and just starting to work thru my new career issues