Last December (12/16) I decided to give AWS a try. I didn’t have much experience with cloud already. In search of a good training course I found aCloudGuru which was also really cheap. Their training courses have a reasonably good coverage and depth for the exam topics.
I was able to knock out 3 associate exams from 0 knowledge to a good pass mark in less than 7 months. I had dedicated about 3-6 hours weekly to practice and study. It also depends on your background and IT experience. Being a developer with many years of experience I was already familiar with almost all the concepts and had a good foundation.
If you really want to learn and not just pass the exam, then you need to go through the training courses, read relevant whitepapers, study FAQs, go through bits of the online manuals and do some hands on development and practices.
The best way to gain more experience if you are not working with AWS on your day job like me is to define personal projects for yourself or get some side projects as a freelancer.