The meaning of "should have p.p."

In a website, there is sentences like the below.

?Whenshould have Clark started wearing glasses?

I am not sure when he should have begun wearing the glasses but it should not have taken this long. He has been seen so many times without the glasses.

In a dictionary 'should have p.p.' usually have meaning to regret about a past activity. (e.g.? You should have been more careful.)

Could you tell me the exact meaning of "should have p.p." in the questioned sentence, and give me another example sentence for this meaning?

["Should have p.p." seems to me to have almost the same meaning with "might have p.p." or "could have p.p." or just "have p.p." I'm not sure. It's just so confusing!]