I have read these questions:
Now my question is NOT about HOW they acquire mass. I understand SSB, and the Higgs mechanism, and Yukagawa coupling.
What these questions do not talk about though is, WHEN the W, Z, and the fermions gain their masses.
And Prahar's answer says:
Thus, we find that if the Higgs field has a base value h, then the Higgs boson (described by f) has mass mHiggs=3λh2−m2−−−−−−−−−√ and the electron (described by ψ) has mass mel=gh. This process is the Higgs mechanism. If h=0, the electron is massless and this was the case a long time ago. At some point, the Higgs field attained a vev (base value) and h became nonzero and the electron was now massive!
This means that the W, Z bozons, and the fermions gain their masses at the SSB, when the Higgs field attained its nonzero VEV, so the W, Z bozons, and the fermions gained their masses at that point, and have mass since then.
And Alfred Centauri's answer says:
In summary, The electroweak bosons become massive in the electroweak-charged Higgs condensate in a way analogous to the photon becoming massive in a superconductor. The matter particles, fermions, become massive in the condensate due to a Yukawa interaction. The Higgs boson would be massive regardless.
So this answer handles the Higgs field as a superconductor, and the W, Z bozons and fermions in it interact with the condensate, and gain their masses by interacting with the field. This means, that the W, Z bozons and fermions need to constantly interact with the Higgs field to gain their masses.
Now the two answers are contradictory. It cannot happen at the same time, that the W, Z bozons and the fermions gained their masses when the Higgs field gained its nonzero VEV at the SSB, and have their masses ever since, and at the same time, the W, Z bozons, and the fermions need to interact with the Higgs fiels constantly, and this constant interaction with the condensate gives them their masses.
Which theory is right, when do the W, Z bozons, and the fermions gain their masses:
a) they gain their masses at the SSB when the Higgs field gained its nonzero VEV
b) they gain their masses whenever they interact with the Higgs field's condensate, that acts like a superconductor