Hello Praveen, Greetings!

Well, if your son has Aadhaar card and passed 12th from a school in India, he wil be eligible for JEE Main. If he doesn't have a Aachar card, he can apply for one as there is still time for JEE Main.

According to the Aadhaar Act, 2016, every resident can apply for an Aadhaar number. A resident is one who has been living in the country for at least 182 days, in the year immediately preceding the date of application for enrolment. If the OCI card holder meets this condition, he or she can apply for Aadhaar.

Otherwise, he would have to opt for the route of DASA

Also, he cannot apply via both JEE Main and DASA.

Thank you, hope this helps.