In theory at least it is only required before you commence a type rating unless of course your employer provides one for you in house (very rare these days).
In anycase I would start firing off any postal applications. The web ones become a bit more tricky as you are effectively faced with lying if you don't have the MCC unless there is a way of ticking the box and adding an explanation. You could tick the MCC completed box and in the "is there anything you would like to add" section add an explanation that you will have the certificate by x date. You can't fail it after all, well in theory you can't although no doubt there is some noddy you missed a class and didn't complete