Ordinarily, on 'Ereb Shabbath (Friday, during the day) we are not permitted to have a large meal of the type that we would not ordinarily have on a week day. That is the case even on Friday morning, because it detracts from the honor of Shabbath.
This does not refer to a Se'uddath Miswah (festive meal), however, that has to be held at that specific time. For instance, when there is a Milah on that day, or a Se'uddah for Sheba' Berakhoth after a wedding, since in these cases the meal must be on that day, it is permitted to be held then. This is so, even though the person may not be able to eat the Friday night Shabbath meal with his usual appetite. However, the meal should be held as early as possible and, in particular, before the 10th hour of the day.
If there is a Se'uddah for a Bar Miswah, if it is actually on the boy's 13th birthday, then it may also be held on Friday during the day. So too a Se'uddath (festive meal) for a Pidyon Habben, provided it is held on the 31st day from when the boy was born, may be held then also.
(See Ben Ish Hai, Shana Sheniyah, Parashath Lech Lecha, Oth Kaf Aleph)
