A positive charge $$q$$ moves with a constant velocity of $$\vec{v} = 3.0 \times 10^6\ \mathrm{m/s}$$ in the $$+y$$-direction. The charge is at the origin at time $$t=0$$. At what time $$t$$ is the magnitude of the magnetic field at point $$P(2.0\ \mathrm{cm}, 0, 0)$$ at its maximum?