He... erm ... pre-programmed it.
As the wide-eyed Finn scrambled for a seat and harness and found
himself wishing for a number of very large, soft pads, Chewbacca
groaned his readiness. Han studied the readouts before him. The
Wookiee raised a hand over his own console. “And…” Han followed the
declining fractions intently. “Now!”
Human and Wookiee hands flew over the main console, supplementing as
best they could the approach and landing information they had
preprogrammed into the Falcon’s instrumentation. Not unexpectedly,
more than one last-second override was required in order to make the
ship do something that was against its nature and perform maneuvers
for which it had never been designed.
SW: The Force Awakens - Official Novelisation
Most of his work at the console seems to be aimed at stopping the ship from aborting the approach rather than actually timing the landing.