I will give Cat 2023...I am in final year...so how will I start....please give me some advice

If you are in your final year now you can give the test even this year, even if you have not prepared much, as it will be a valuable practice experience and will give you an idea as to the real feel of the exam. For now you can register for Cracku crash course to get an effective intro to the syllabus, and for their mock test and daily test series for the practice. The Cracku support resources and lectures are top notch. Additionally I would recommend Arun Sharma's study material for extra practice.