  We investigate the timescale on which quantum corrections alter the
predictions of classical field theory for scalar field dark matter. This is
accomplished by including second order terms in the evolution proportional to
the covariance of the field operators. When this covariance is no longer small
compared to the mean field value, we say that the system has reached the
``quantum breaktime" and the predictions of classical field theory will begin
to differ from those of the full quantum theory. While holding the classical
field theory evolution fixed, we determine the change of the quantum breaktime
as total occupation number is increased. This provides a novel numerical
estimation of the breaktime based at high occupations $n_{tot}$ and mode number
$N=256$. We study the collapse of a sinusoidal overdensity in a single spatial
dimension. We find that the breaktime scales as $\log(n_{tot})$ prior to shell
crossing and then then as a powerlaw following the collapse. If we assume that
the collapsing phase is representative of halos undergoing nonlinear growth,
this implies that the quantum breaktime of typical systems may be as large as
$\sim 30$ of dynamical times even at occupations of $n_{tot}\sim 10^{100}$.
