Please read the it on the website . I read it again from the link you sent . You can apply if your study permit was valid, you changed your status to a visitor visa or you had submitted a study permit extension and are waiting for an answer. My study permit expired on the 30th of March and I did an extension late in the beggining of Feb.
So I think one can apply if you have implied status .please read it on the link you posted on those who qualify.
I'm not sure what you mean by last six months