  The process of condensation in the system of scalar Bosons with weak $\lambda
\phi^4$ interaction is considered. Boltzmann kinetic equation is solved
numerically. Bose condensation proceeds in two stages: At the first stage
condensate is still absent but there is non-zero inflow of particles towards
$\vec{{\bf p}} = 0$ and the distribution function at $\vec{{\bf p}} = 0$ grows
from finite values to infinity. At the second stage there are two components,
condensate and particles, reaching their equilibrium values. We show that the
evolution in both stages proceeds in a self - similar way and find the time
needed for condensation, which is finite.
