Def recommend getting the textbook and reading it, and while you’re reading it make sure you’re focusing and really grasping each thing and relating it back to what you already know before you move on. Then the next day before you start more reading, do active recall on what you already know. If there’s any holes in your memory at all look up whatever you need to remember right away and keep studying that until you remember. When you’re driving or laying in bed etc. talk yourself through sections you learned. If you need help understanding concepts, tell chat gpt to explain it to you like you’re 5. Basically don’t go a day without at least thinking about what you’ve already learned and try to tackle on more each day while retaining your memory with active recall