It's tough you try to score good in both the exams. But yes if you smartly prepare for JEE Mains and JEE Advance, then you surely score well in boards as well. So yes make a proper timetable first of all, know all the goals that you need to achieve, get the perfect mcq books for PCM all 3 subjects and stay honest and hardworking and dedicated towards your goal. And try to solve as many as problems as you can.

Best wishes. Thank you.