Hello Ashray,

Aapko dono exams manage krne pdenge. But, JEE Main ya fir Board exams k liye jab prepare kr rhe hote hai, to subjects and topics dono hi same hote hai. To zyada farak nhi pdta.

Agar tumhe abhi bhi nhi lagta ki tmhe January wala ni dena chahiye to mat do. First focus on your Board and then attempt for the JEE Main April exam.

But, i would suggest you ki tum Mock tests attempt kro and side by side boards ki preparation kro. Boards pe focus kro. And, January wale exam k liye bhi apply krdo. Tmhe atleast kch to idea ho jaega exam ka ki kaise aaega and kaha tmhe zyada mehnat krne ki khaas zarurat hai.

All the best!