If a person will have to prepare for Shabbos after reaching his destination,
the poskim disagree whether he may leave for another city if he will arrive
after one third of the day has passed. But the Bach holds that a person can
depart for another city even after
chatzos if he estimates that he will arrive at his destination
well before the Shabbos and have ample time to prepare for Shabbos, and this
is the opinion of the later poskim. If all preparations for Shabbos have
already been made so that he will not have to prepare the Shabbos meals
after he arrives, a person is permitted to set out for another city on erev
Shabbos even after chatzos.