Without first testing the knowledge you have gained and whether it is enough or you need more practise, it is not advisable to drop a year. You need to first appear for JEE Advanced check the result and see if yu can get a seat allotted. And then based on the results and score, you need to evaluate your options. If you are so close by to the seat or the marks that are required for a seat in IIT, may be then you can consider dropping a year but again even that is not advisable because you lose focus and the passions with which you have started when the exams are almost a year away. So first appear for JEE Mains, check the eligibility of qualifying for JEE Advanced and then give the exam. That way you know where you are good at but where you need to improve. With a proper analysis and understanding of your current knowledge base, you can take a call whether you should join a long term coaching class or prepare at home. This is important because a year in the long run will cost you dearly and you cannot take a decision without first evaluating everything.