hi,

see there is enough time for you to prepare for jee main exam, however jee advance exam is bit tougher than jee main , however if you have good concept about board exam syllabus you may attempt  around 60% scores in jee main. however to get more than 95+ percentile you must study previous years questions papers, solve the mcq papers and give mock test regularly to get speed at solving problems.

There is various online coaching available for students to prepare jee main and advance test. also there is free video lectures available on net which you can study.

so make a proper strategy and once your 80% board exam syllabus completed you may start preparing for jee main exam. jee main exam can be attempted consecutively three years starting from year of passing of 12th course. jee advance can be attempted only 2 times consecutively starting from year of passing of 12th course.

careers360 has online coaching for jee main , it includes online lecture series, mock test, doubt solving sessions, previous years solved  papers. overall this is a complete package to boost your performance.

to know in details follow the below link:

https://learn.careers360.com/