A major difference between attempting Core Formation and Foundation Establishment is that the former can be broken down into several stages. It doesn't require passing through three hurdles in one go like Foundation Establishment does.
So, when a Perfect Foundation Establishment Cultivator says they are about to attempt Core Formation, they have, in fact, been working on it for years.
They have already completed the steps of converting liquid Magical Power into True Essence, perfecting the physical body, achieving a state where Water and Fire are in Harmony, and where Kan and Li Intersect.
For the most part, the nascent form of a radiant, perfectly round Golden Core has already taken shape in their Dantian.
Only the final step remains: to infuse one's Divine Sense into the Golden Core, forging a connection that allows one's Essence, Qi, and Spirit to successfully metamorphose, sublimating the very essence of one's life.
