My aim is to study B.Arch. To which exams should I prepare between NATA and AIEEE? How to prepare for both these exams simultaneously? How much time will I need to complete the preparation? Tell the important dates of both these exams.

Im 12th std.Im gonna face my board exam in march-2013. Im in coimbatore. I want to study B.arch. My aim.
1.I have a confusion to prepare either for NATA or for AIEEE b.arch. I'd like to write both exams. Could you guide me how to prepare for both exams simultaneously? how much time does it need to prepare good for these exams?
2.I'd like to know the exam dates for both exams.Please tell.
3.And is there any good coaching classes in Coimbatore for NATA/AIEEE B.ARCH??