It is pretty common for people who are 40 and over to wear bifocals for they start having problems reading things up close. But those who were near sighted before age 40 while having problem see things further away still in the need of bifocal reading glasses. Wear proper eyeglasses as your eye doctor recommended, never mind the age problem.
Go to your eye doctor to have an eye exam. If you do need them, then your doctor will recommend to you. If you don't have to wear them, you'd better not get them. I have never heard that people who are too young cannot wear bifocals.