In The Absolutely True Diary of a Part-time Indian, how old was Junior when he began wearing eyeglasses?

In The Absolutely True Diary of a Part-time Indian, Junior started wearing eyeglasses when he was just three years old.  Ever since birth, Junior suffered from physical ailments, the most immediate being hydrocephalus.  He had surgery when he was only six months old. From there, other physical problems surfaced, including him being nearsighted in one eye and farsighted in the other, causing him to start wearing glasses at three years old.  When Junior's teeth finally came in, he ended up with 42, which is 10 more than standard.  In addition to these, Junior also suffers seizures.  As a result, Junior is often bullied on the reservation.  The glasses that he wears are thick and rimmed in black plastic, which others think look funny.  So, Junior has worn glasses since the age of three.