Post processor selection is indeed a critical thing!
For your learning pathway, try to "do" the projects (or similar with the same kinds of steps and cuts) as you work through the tutorials when time and material allows. You can cut foam insulation for practice or scrap lumber you did a quick glue up on, MDF for flat stuff including scraps you might have lying about etc. Nothing beats actually making stuff to learn, even if they are intentionally "throw away" projects. Some of this learning can be used to make things for the shop...stuff for organization of tools, fixtures/jigs, etc. It's all really good time spent and good for learning.
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The most expensive tool is the one you buy "cheaply" and often...