You do not need to join the AAPC until you register for the CPC exam. You MIGHT join sooner if you plan to start attending your local chapter's meetings. Those are fantastic places to network and hear some educational presentations, as well as find out about the local job scene. They almost always announce local jobs during meetings. Some of our students do get their jobs partly because of this type of networking with the AAPC.
It's not necessary to be an AHIMA member in order to take the CCS or hold the credential, but you might consider it if the discount on the exam and other AHIMA materials appeals to you. The local AHIMA groups are more regional than local and are, on the whole, generally a lot less approachable and helpful than those of the AAPC.
Now, however, is the appropriate time for you to begin familiarizing yourself with the websites of both of those organizations. They both contain comprehensive information about their organization and their exams. Learn how to find information on those websites. You should locate that information and compile a folder for both the CPC and the CCS. You do want to know the similarities and differences between them. The exams are quite different, with differences in content, book requirements, testing rules and recommendations, and the type and quantity of notes that you are allowed to have in your code books. (We provide specific exam-related information at the appropriate time in Module 3, so don't worry about that.)
You do not want to be running about the Internet asking random people for advice about these exams simply because you will be given misinformation from people who don't understand them or have no idea what you're talking about. Worse, you may also risk developing a reputation among potential employers for being unprepared and unable to do your own research.