I can tell you what I did when I attended Concept Design Academy.

In my first term, I took.. probably what was way too many classes. I signed up for Intro to Perspective, Vis Com: Dynamic Sketching, Analytical Figure Drawing and Sketching for Environment. After my first week of classes however, I definitely realized how in over my head I was with the course load, and having sat through the first class of Intro to Perspective, I realized just how demanding the homework for it would be. I did find that Vis Com: Dynamic Sketching (the course that served as the foundation for what ultimately became Drawabox) covered a lot of similar concepts but in a much more organic, flexible fashion, and I decided that it would be more widely applicable to what I wanted to focus on at the time than the Intro to Perspective course. So I made a call - I dropped Intro to Perspective (while I was still within the threshold to receive a 50% refund). In retrospect, that call was definitely the right one.

Drawabox and Dynamic Sketching are not perspective courses, but they do share certain concepts - specifically the understanding of how the things we draw exist in 3D space. Perspective courses themselves tend to focus very much on introducing you to a lot of tools that you can employ to solve complex perspective problems, but when it comes to things like figure drawing, you're really dealing with that abstracted level of spatial awareness rather than memorization of specific, strict perspective rules. If anything, that's what I hoped to pull out of Dynamic Sketching and focus on with Drawabox. It's about learning how to work in 3D space - not about memorizing the rules.

Long story short, you should feel comfortable taking Kevin's Analytical Figure Drawing course right from the get-go, and I think it would be hugely beneficial for you to do so (whether you choose to take Intro to Perspective alongside it or not). I'm not sure if you're taking it in person or online (I attended before they offered online courses, so my experience with his instruction may differ) but when I took the class with him, he did a fantastic job of assessing where your skills were, and what you needed at that moment to help develop your understanding of how to draw and construct figures. It was very much a course that required no prerequisites.

That said, I do think that the spatial reasoning skills you've demonstrated thus far in Drawabox position you well to jump into his course, and I expect that doing so will also have its own positive impact on those same spatial reasoning skills. So you should feel free to do so without fear of jumping in too early.