How to prepare for IAT in class 12th?

I just came in class 12th and I recently came across IAT and IISERs. The problem is I had no idea of this exam and BS-MS course in my class 11th so I didn't do any entrance level preparation in class 11th as I thought I would give CUET and go for a bsc chem course in DU.

But now I am regretting it, its not like I have wasted my entire 11th or smth but I studied only basic CBSE level syllabus especially for maths and physics.Also I am a pcm student so I would also have to study bio from scratch too.

Given my situation, how do I prepare for IAT 2027? I don't have a coaching too so kindly suggest some yt channels, resources too🙏🏼 Also as a pcm student, how should I do my bio?

Should I give CUET too? Is taking a drop and preparing for next year worth it just in case I don't make it this year?