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It used to be the custom for the bachelor dinner to take place the night before the wedding. Now, however, the bridesmaids' and ushers' dinner is usually on that night, for a groom realizes that he and his attendants need some time in which to recover sufficiently to be able to distinguish the altar from the organ and walk up the aisle with no mishaps.

Alice-Leone Moats (1933). “No Nice Girl Swears”, New York : A. A. Knopf
It used to be the custom for the bachelor dinner to take place the night before the wedding. Now, however, the bridesmaids' and ushers' dinner is usually on that night, for a groom realizes that he and his attendants