One of the biggest mistake students makes " Not knowing about what they are going to learn". Yes, it's true, When you dont know the basic or an overview of the subject, then it takes extra time, and you need to keep reading multiple times.
Whenever we plan to go for training for a specific duration on any course :
1) First and foremost, do some homework by gathering some basic information on the course.
2) Plan your Duration like 1 or 2 months
3) Know the contents or the full syllabus of the course, which gives the road map for the upcoming days.
4) Dedicate specific time and make sure that there is continuity in studying
5) Do not drag your study time. It makes you lose interest, and you will feel like boring, which ultimately delay your overall duration.
6) Always spare some time daily to review what was learnt in previous classes; this makes you remember till you complete the course or syllabus.
Follow the above simple steps and see the results, how they are going to be!