Started in Easter and got a clean streak of 9s. I WOULD NOT suggest this as it did become somewhat stressful a couple of weeks before the tests and I was revising between 6-10 hours everyday.
I highly suggest you start revising lightly now and get together all revision materials and notes on all your courses. Repeatedly go over your notes every couple of weeks, especially for the stuff you suck at the most. After Easter you need to ask yourself "if I had a test tomorrow, what would I struggle with the most" and go over that while doing loads of past questions. Also learn how to answer the questions --> EXAM TECHNIQUE.
If you really want to get 9s across multiple subjects, focus on understanding the content and why you do certain things to solve a problem or why a formula works as these are the types of things you will need to know for the last questions the tests.
As a side note: with our maths GCSE we had 3 papers. The first 2 were not difficult and found it easy to understand the questions and answer them. The 3rd paper was a lot harder and was defiantly the differentiating factor between the 'very best' and 'good'.
Another note: Your English lit teacher should be able to predict the questions that will come up
Final note: Exam boards are businesses so they will be highly unlikely to make you answer multiple weird questions as it risks schools/colleges switching exam boards = lost business = predictable questions that shouldn't be too outlandish.