All right, you can make a little bit of fun of me for this one because a.) I used Cloud Native mode when I could have used the "standard" mode and made it MUCH easier. But I thought I'd restrict myself to the same limitations others had when Cloud 9 hit the community (e.g. no standard mode, so no generate rows). And b.) I was thinking "on canvas" as I went and had a few ideas bouncing around, so my workflow has some extraneous bits that I didn't clean up as I moved between ideas. And c.) I'll admit, I completely forgot the +1 at first for date calcs (that's not much of a spoiler) and I wasted some time walking back through it to see if I'd messed up my dates anywhere else before I realized the problem.
This opened in Cloud Native and it refused to let me switch to Standard no matter what I tried (short of just starting from scratch), so I did this without Generate Rows, like many who came before me. It, uhh, was rough :D