It is really a good thing that you have completed your syllabus. But there is no harm on repeating. You should practise as many mock tests or sample papers as you can. For revision, divide the syllabus into Class 11 and Class 12 and the topics as "Need to Learn", "Weak" and "Strong". Now it is important to check the weightage of each topic. In Mathematics, Co-ordinate Geometry gets 5 questions. Limits, Continuity and Differentiability, Integral Calculus get 3 questions slot each. The rest get 2 and 1 questions slot. So plan your preparation accordingly. For complete breakdown, please read our article: https://engineering.careers360.com/articles/jee-main-syllabus-weightage .. If you are planning on joining any crash courses, check this: https://learn.careers360.com/knockout-jee-main-april/