How soon is too soon to start preparing?

to @rickle1 point, I found this article interesting

" 1 out of 4 perfect SAT scores get rejected by Harvard. 3 out of 5 valedictorians get rejected by uPenn and Duke"

the mathematical odds of acceptances for MT at CMU ( 14 out of 2000?), Michigan, etc etc are lower than academic acceptances into these Ivy and" Ivy- like" schools

https://patch.com/us/across-america/investigating-who-gets-harvard-why#:~:text=This%20means%2C%20for%20example%2C%20Harvard,of%20five%20high%20school%20valedictorians.

not to beat a dead horse, it certainly happens for some every year but to not cast a wide net would be doing your kid a disservice IMHO