I started my first bucket list when I was a freshman in high school. That was eight years ago, and I no longer have that phone thanks to a pick-pocket in Naples, Italy. I have since attempted to rewrite my bucket list and cross off the things I have done. I don't think there is ever a wrong time to start a bucket list. It is something you can cross off at any time in your life, and I want to do everything on this list and keep adding more.
Hopefully, this gives you the inspiration to start your own. (PS, all the ones with an exclamation point I have done!)