Based on my n=1 experience and a general trend I personally have seen on Reddit, I second
@iforget2 in that the NBMEs represent your floor, especially if there is a discrepancy between your NBMEs and UWorld scores. In my case, my NBMEs averaged out to ~230 while both UWSAs and the UWorld Qbank averaged out to ~247 and I ended up with a 235. I think if there is a discrepancy, you can realistically expect to land somewhere in between those two averages with the potential to score higher or lower. In many cases, the people who have scored lower than predicted (like me) had higher UWorld scores and lower NBME scores and the predictor gave UWorld too much credit when actually they landed right about where they should have based on all of their practice tests as a whole. Of all my practice tests, my NBMEs ended up being closer to my actual score though I think I could've scored a lot closer to my UWorld average if I hadn't had a handful of brain farts on stuff I would likely answer correctly 99 times out of 100. There's so many variables that play into this and while the predictor gives you a general ballpark of where you can expect to land, I would definitely still take it with a grain of salt and head into the exam with the expectation that you're probably more likely to fall somewhere in your CI rather than right at your predicted score.