Isca just read pm. Learn it by heart. Read all theory costing questions from pm. And do OR/Qt part. You can get 50 in both. If u aint sure about this then just attempt for a exemption in idt or dt
Think of utilizing the remaining fifteen odd days in a more constructive and positive way. You have done all the hard work and now do not give up at this final moment. Believe in your inner strength and surely you are bound to reach your goal. Wish you best of luck.
PM for ISCA no doubt ...learn the headings by heart, seriously its worth it !
And for costing, read as many as question you can .....even if you can't solve you can have good grasp of questions enough to handle the technicalities.