  Heavy quark $R_{AA}$ and $v_2$ have been calculated at RHIC energy
considering initial conditions with and without pre-equilibrium phase to
highlight the effect of the latter on heavy quark observables. The momentum
evolution of the heavy quark has been studied by means of the Boltzmann
transport equation. To model the pre-equilibrium phase we have used the KLN
initial condition. We have found that the pre-equilibrium phase impacts the
$R_{AA}$ of about 20-25 $\%$ whereas the impact on $v_2$ is very negligible. We
have also calculated heavy quark $R_{AA}$ and $v_2$ in the case of
initializations with early thermalized quark-gluon plasma. We have checked that
the particular form of the initial spectrum is not very important for $R_{AA}$,
the larger energy density being more important. In fact, comparing the results
obtained within the two initializations we have found that one can mimic the
impact of the pre-equilibrium phase using a early thermalized QGP medium.
