I wont give you advice as I don't really know, but only my opinion.
I know the MCC isn't something that you need to renew so with that in mind it doesn't really matter when. I'm under the impression that the MCC trains you in multicrew situations... emergencys, following departure plates etc.. I would imagine you'd have to have your IR already done but as I said, I don't know.
I'm sure someone else will have a better answer for you..