I don’t think it’s going to give you an “edge” I have two math kids and they had mixed acceptances( not accepted to every school). They aren’t math nerds either. Both are accomplished in sports. One had perfect math on SSAT (not the meatiest kid), the other was 4 years ahead. I think other math/STEM factors had more impact.
Also, taking Precalc in 18 weeks isn’t a good idea. One of my kids skipped several years of math along the way but did the work in other ways. The only thing I’d advise skipping is trig. ( Can be learned in a very short time, IMO and the opinion of my kids).
On the other hand, I think a kid who went deeper in math might have an edge. The kid who did a project with math or studied math to fully understand a point might demonstrate aptitude and more. That seems to be what AOs want to talk about. One BS AO told me all about math kids like my youngest and what they were doing.
BTW, agree with other posters, 9th grade calc students aren’t that unusual. In China that’s pretty much the norm. And some schools in CA have a track so kids naturally follow that. Homeschoolers are often advanced learners as well. And some kids just love math so they self teach.