To add to what's already been said, methods 3/4 actually doesn't have that much more 'content' than methods 1/2. Basically everything up to circular functions is mostly the same material, and calculus has only a bit of new stuff. imo probability and statistics are the only topics that significantly expand on what you learned in 1/2. For the other topics, you don't really learn any fundamentally new concepts like how you will be learning differentiation and integration in 1/2.
The difference comes from the manner in which you are expected to apply what you have learned. While each of the topics in methods 1/2 might be more 'isolated' in that you might do a test on functions, and then a test on polynomials, and then a test on logs and exponentials, methods 3/4 requires you to stitch everything together and use concepts from different topics in the
same question. This actually makes things a fair bit harder, as you can no longer rely on just memorising rules and formulas - you have to truly understand how to use these rules and formulas, and at times you have to think a bit creatively. Thus, it would be optimal for you if you take special care during 1/2 to really try to deeply understand everything that you learn. It will definitely make 3/4 more straightforward.
No stress though, you still have a lot of time to learn everything