  Many quiescent galaxies discovered in the early Universe by \textit{JWST}
raise fundamental questions on when and how these galaxies became and stayed
quenched. Making use of the latest version of the semi-analytic model GAEA that
provides good agreement with the observed quenched fractions up to $z\sim 3$,
we make predictions for the expected fractions of quiescent galaxies up to
$z\sim 7$ and analyze the main quenching mechanism. We find that in a simulated
box of $685~{\rm Mpc}$ on a side, the first quenched massive ($M_{\star} \sim
10^{11} {\rm M}_{\odot}$), Milky Way mass, and low mass ($M_{\star} \sim
10^{9.5} {\rm M}_{\odot}$ ) galaxies appear at $z\sim 4.5$, $z\sim 6.2$, and
before $z = 7$. Most quenched galaxies identified at early redshifts remain
quenched for more than 1 Gyr. Independently of galaxy stellar mass, the
dominant quenching mechanism at high redshift is accretion disk feedback
(quasar winds) from a central massive black hole, which is triggered by mergers
in massive and MW-mass galaxies, and by disk instabilities in low-mass
galaxies. Environmental stripping becomes increasingly more important at lower
redshift.
