Temporal lag between various spatial crossing and star formation events. In blue (orange), we show the time difference between the moment that a tracer last crossed R_200c (2 R_SF, 1/2), i.e., halo infall (galaxy infall) and that when its parent gas cell is converted into a star particle. The time gap between the two infall events (green) is contrasted against the time elapsed between the first and the last crossing of 2 R_SF, 1/2 (red). All curves show medians across the galaxy population and the value for each galaxy is also the median of all its tracers that actually undergo the event(s), always taking absolute values (see text). Gas accretion onto galaxies proceeds over several ∼Gyr, while the eventual collapse of ISM gas into stars occurs on shorter time scales (≲Gyr), as long as it is not recycled back into the halo due to feedback.