Most people don't just decide that "hey, today is a good day for me to start wearing glasses, wouldn't it be cool!?"
For young kids, it's usually when they start doing badly in classes or people notice they are squinting. For adults, it's having trouble with things like the DMV exam, caught by routine checkups, or when they notice their peers can see much better than they can.
I could also give you endless anecdotes "proving" the opposite point, that wearing glasses can slow down or stop the progress, but why bother. That's all they are, they are not facts.