Mechanical engineering student, how long does it actually take to become a design engineer?

I’ve done my research online and come to the conclusion that absolutely nobody actually knows. I’ve seen numbers ranging from the day you graduate to 15 years in the industry. My professors have been little help, their answers ranging from probably never, to five years, to no idea. So I come here for what will likely be more of the same. How long did it take you to become a design engineer? How long does it take in your observations to begin a design role?