A 4 is very easy to get, however, it is only considered a limit pass. You can get a 4 despite making several mistakes, skipping a lot of questions, and having a weak understanding of the curriculum. Starting two or three months in advance is definitely a good starting point for planning your review. It's a nice, round amount of time that it's easy to fit your GCSE subjects into.
These kinds of questions are often cited in attacks on the GCSE as silly. But these are questions that differentiate students who are on course to earn a G from students who could earn an F. In many other countries, these students would be taking another grade, or none at all. Even if you study half-heartedly throughout the year and raise your game as you approach your exams, getting a 6 on your GCSE shouldn't be too difficult.
GCSE mathematics needs you to really understand what you're doing and to know what the upper and lower bounds really mean. Interestingly, in places where students excel in mathematics, the emphasis is on thinking like a mathematician rather than covering miles of content a few inches deep. Put it into practice and work hard now and you'll have a very good chance of nailing it in your exams and getting the grade you're looking for. However, in the future, I think it is vital that grade 4 represents a consistent measure of mathematical competence.
It should be changed to a more attractive name, such as Essential Mathematics or Standard, especially now that the content has increased. Getting a 6 is not difficult at all and you should easily get a 6 on your GCSE if you don't make a significant number of mistakes. What you need to know for your GCSE math will depend on the curriculum you're sitting on, and whether you're sitting at the base or at a higher level. Of course, you can't include pipe cleaner models in your GCSE math tests, but practicing with them helps you develop the visualization skills you need to be able to answer questions without them.
In fact, Ofqual found that GCSE's math tests contained the easiest questions of any test for 15-16 year olds from a variety of countries. This score expresses the student's inability to demonstrate sufficient use of knowledge or application of Mathematics to achieve any of the grading scores below. If it's any consolation to students who struggled with this, this requires a conceptual leap similar to a question that Ofqual's mathematicians panel thought was one of the most difficult, also posed by Edexcel. This is because GCSE Further Maths has a broad syllabus, complex and difficult to understand concepts, challenging questions on exams, hard grades, and requires a lot of independent study.
Ranking them will surely give you a big advantage in the review and help you feel much more confident in your GCSE math skills. The new mathematical GCSEs were designed to be different from the old GCSE A* to G, so you can't really compare the new with the old.