Yeah definitely, you can do that and I personally believe thats a very good Strategy for Preparation. In Std 11 you may prepare from excellent preparation resources, educators and materials available on Unacademy, and once in Std 12, you may take a 1 year a good Test Series and Preparation Course either Online or Offline from some of the Best Management Exam Coachings like TIME or Career Launcher.

For more information about IPMAT do follow the link below

https://bschool.careers360.com/exams/ipmat/amp

For more information about IPMAT Syllabus do follow the link below

https://bschool.careers360.com/articles/ipmat-syllabus