Yes, you can apply for forthcoming exams. Provided your date of election is Aug 31 (for latest Winter exam) or Feb 28 (for latest Summer exam).
Just fill the exam form (in the period prescribed, Generally Feb 15 to April 20 for Summer and Aug 16 to Oct 20 for Winter exams). Send this exam form with DD of requisite fee by speed post (as you can track speed post, do not send this by private courier service). Keep a Xerox of exam form and DD in your records (as safety measure).
Your identity card/other docs etc will come late.