Hi,
I think medical should be after ITA, PC however depends on the countries you need them from, the USA for example takes a while so you should do this early. I would advise that you should do them before ITA only if you are somewhat new in the EE pool and your score has been drawn in previous draws, because you can be a little certain that you will get ITA soon, but if your score is lower than 453, then I suggest you hold on till you get ITA because they might expire before you get ITA and waste your time and money.