I have seen 4 years old singing like a professional. You just need training and continuous practice to be perfect. If you think you can do it, start right away! learn and practice! I hope it helps.
I agree with everyone - that you are never too old to start learning something new. I started playing piano when I was 10 years old. However, I have learned even more from music classes and private piano lessons through high school and college. I have played in bands with other musicians of all skill levels and I'm currently trying to learn how to play ukulele. It is a lifelong process and you can constantly learn a new song, new chords, etc.
I feel like a good, strong knowledge of music can help you learn to play different instruments or sing if that interests you. Never stop learning and trying new things!
Best wishes to you in your musical, educational and career goals!