  Isolated many-body quantum systems quenched far from equilibrium can
eventually equilibrate, but it is not yet clear how long they take to do so. To
answer this question, we use exact numerical methods and analyze the entire
evolution, from perturbation to equilibration, of a paradigmatic disordered
many-body quantum system in the chaotic regime. We investigate how the
equilibration time depends on the system size and observables. We show that if
dynamical manifestations of spectral correlations in the form of the
correlation hole ("ramp") are taken into account, the time for equilibration
scales exponentially with system size, while if they are neglected, the scaling
is better described by a power law with system size, though with an exponent
larger than what is expected for diffusive transport.
