Honestly all these materials are not needed. The Barron’s book alone plus free online tests would be enough, but the flashcards may be handy as memorizing vocab from a review book can be tedious. Definitely use crash course videos to learn certain concepts visually. All of this should set you up for a 4 or 5.
If it is me, I will just read and study using the Barron’s book, then take some practice tests. Doing all of these and understanding everything in the book would gurantee at least a 4.
^ Accomodate for your learning style. One of my kids is very much an auditory learner. Videos are immensely helpful for them. My D got a 5 but started much earlier in the year. So I think that a 3 or 4 at this point is possible.
I really like the crash course videos as a review tool personally. I took the class but would lead the review book (which sometimes taught more than the teacher) and then watch the videos to make sure I understood.