Lolli.. you can take as much time as you want (within your month). Start with a "beginner" course (because they do have different levels). The idea is to get an overview of the tools and techniques. Don't worry about trying to learn everything all at once. Absorb the general concepts and buzz words. You'll find that later, you'll face an image that, for example, may need to be lightened in selected areas, you will remember you "saw that on Lynda and remember dodge and burn or Screen blend mode. THEN you can go to the Photoshop Help menu and search on "dodge/burn" or "lighten an image" to refresh your memory and learn more.
I hate that they don't print manuals any more. When I would get a new program, I would fix a pot of tea and start paging through the manual reading the sample captions and headlines. Then I'd get into a project and face a situation and say to myself... I know Photoshop can fix this, I saw it in the manual. Then I would search the manual index for key words that would apply. (clone, color, heal etc.)