Personal political advice is that it is more appropriate to start reviewing politics after the National Day. Don't memorize political review. Just buy an analysis of the political postgraduate entrance examination outline compiled by the Ministry of Education, also called Little Red Book. Other materials can be read in 20 questions 20 days before the exam (in fact, I personally think the best is the last point written by Mi Peng, but it seems that only Hunan has it).
The reference material of mathematics is mainly to buy a review book for postgraduate entrance examination written by Li Yongle, because I used this book last year. Of course, you can also consider the review book for postgraduate entrance examination written by Chen Wendeng. I think the title of Chen Wendeng's book is more difficult, and the way to solve it is more partial. You can weigh it yourself.
Summer vacation is the prime time for exam review, so you can prepare wholeheartedly. I suggest that you can adjust the review time to the same as the exam time for postgraduate entrance examination. Get up in the morning and recite words in the morning, review math in the afternoon, review English in the afternoon and review math in the evening, so it is a big deal to spend more time.
If you have high goals, you can also start the first round of professional course review in the summer vacation. It is suggested that the review of specialized courses be conducted in the evening. In short, summer vacation time is precious, and math and English are the key points.
I hope you succeed in the postgraduate entrance examination!