What I really have to say as a teacher is that everyone learns at different rates and everyone has a different learning style. If you are good at learning from reading information but you an audio or video leaner then you are not getting the most for your effort.
Also, it is important to start building stuff after you get a grasp on a particular technology.
As a frame of reference. To learn a full stack working full time, I would give a ball park of six months.