Hello!
Anyway, my question is that if I should wait to prepare for the test since there are some ways to study for it or I should go for it.
Wait and prepare! For any vacant posotion, a certain number of applicants are invited to the tests, which means, that the applicants compete against each other, not against a passing mark (as for example in your ATPL exams). Only the two or three best applicants out of ten in each test will pass. And you can be sure that nine out of ten candidates will come well prepared. Without specific preparation, you stand zero chances of passing, even if you are a Nobel-price candidate otherwise.
Good luck!