I just submitted the short note for publication! I'm so happy to have cleared this hurdle. I wrote this in October, submitted it in January and got it right back without review, and have heavily revised it over the last 5 months and added more data. So, here it goes again!
This paper is nothing big, and it's going to a journal with an impact factor <1. Still, I've done the vast majority of this myself (with advice from the coauthors), so it's an accomplishment for me. I've been hearing that first papers take a long time, and this is certainly the case for me. Maybe my next one will go more quickly!