I see, well I thought you're not too depp into coding. I may be wrong for game dev in common, but I create my levels based on my programming knowlegde to optimize structures of level design and code that interact with each other for solutions that bring up as few problems as possible (=> lowest programming effort, or formally know as the "minimum principle"). I guess you could run into heavy problems when you start with design, since you'll notice that you gotta change a lot when you start coding and the problems how to bring both into one "boat" occur.


Start with the code, and create your levels around the code. You'll have to do that anyway, but starting with design will result in design -> code -> redesign.