Generally speaking, you should first determine your own direction before taking the postgraduate entrance examination. For example, when choosing internal surgery in clinic, we should consider our own interests and abilities as well as gender factors.
As for the time to start preparing, if you have a solid foundation and strong English ability, it will take about half a year to prepare from the summer vacation after your senior year, during which English, political surprise and comprehensive consolidation are the main reasons.
If you have a weak foundation and poor English, you need to be prepared for a long-term war of resistance, especially English. You should start paying attention two years in advance, pay more attention to vocabulary, reading and writing, and pay attention to the real questions. Only in this way can we hope to achieve our goal.
As for politics, you don't need to spend too much energy. After reading through the outline, you can collect more information about the remedial classes for postgraduate entrance examination in the last three months, and make a targeted breakthrough, which can achieve ideal results.