One must eat immediately after reciting Kiddush on Shabbos, in
the very spot where Kiddush was said, unless he specifically had
in mind to eat in a different room or part of the building. If he is
thmun others with Kiddush they must also eat immediately. If they
ate but he didn’t, they are still tmuh. (MB 273)
>>>Adopted from the shiurim of Ha Rav Leible Sternberg