Hi,

For JEE Mains, since the application window for the April session ended on 4th April,2020. You cannot apply for April session, but you still have May session left so you can try to apply for it on time. The registration for May session will take place after the April session will end so that will probably be in the month of May itself.

It is advisable to regularly check the official site for updates.

I hope this helped you.