People who have cleared mains exam, please guide.

I find pre and mains syllabus to be vastly different. Maybe except for English as it is comprehension leaning in both the pre and mains. But I need you guidence regarding the other 3 subjects. How do you prepare for mains and how many months of practice is required for quants and reasoning. And what are the good sources for it? And how many months of GA should be covered and from which source.

Any guidence will be valuable.