well, what I did , is I redo my police clearance when I redid my medical exam, I didn't wait them to ask me, cause I didn;t need any delay over the delay I already had in my application. But, as I read in some post here, in some country, they won't accept the medical exam from you unless they send you a specific form, so I don't know , some people here say , wait until asked for and some say no, do it before they ask you, so you won't get any delay in your process. But what I am sure of it, is that they don't issue a visa unless they have a valid medical exam.
Good luck