Please advise: Studying for OCS/Management Level objective tests simultaneously

You really don't think you need 3 whole months to prepare the OCS? I don't know, but have you really gone through the materials and example (GymFit) question provided by CIMA? You would better not underestimate the Case Study exam, as unlike the operational pillar exams, it is not testing your calculation skills, but all the objectivity as well as implementation of the knowledge. In other words, it is testing by making you explain the logic of the knowledge, not asking us to do any more calculation. But if you are confident that you have mastered all the skills and can really pass the OCS in one-take, then I can't see why you cannot study E2 or F2 so as to save time. But again if you are confident that you can pass P1. P1 is not as easy as you think. You can fail it not because you haven't studied the material well, but your calculation is a bit slow and you cannot finish all the questions. Good luck!