10. Drinking the wine:[1]

If a Bris is taking place on Shabbos prior to the congregation saying Kiddush, then it is customary to give the wine to a child [who is over the age of Chinuch[2]] to drink.[3] If there is no child present, then the person who said the blessing should drink it having in mind to fulfill his obligation of Kiddush through drinking a full Revius of the wine.[4] If possible, it is best for him to drink an additional Revius, in addition to the majority of a Revius which he is to drink to fulfill his obligation of Kiddush.[5] [This, however, is only necessary if he does not plan on eating any Mezonos after drinking the wine. If he does plan on eating Mezonos after drinking the wine, then he may even initially drink from it and it is not necessary to give it to a child and to drink more than the majority of a Revius.[6]]

[1] See Admur 273:9; Rama 273:5; Levush 273; Perisha 273:4; Shevach Habris 18:12; SSH”K 54:23; Piskeiy Teshuvos 273:11

[2] See Admur 190:4; 621:5; M”A 559:9; Beir Heiytiv 621:11

Other opinions: Some Poskim rule that it may even initially be given to a Katan who is under the age of Chinuch. [2^nd opinion in Admur 190:4]

[3] The reason: As it is forbidden for an adult to eat or drink before kiddush and hence we give it to a child.

[4] Admur ibid; Implication of Rama ibid; Even Heozer 273

The reason: One is to drink a full Revius in order to fulfill his obligation of Kiddush Bemakom Seuda according to those who hold that a single Revius of Kiddush suffices. [See Admur ibid]

[5] Admur ibid; Taz 273:4; Levush 273; Bach 273; See M”A 273:12; Elya Raba 273:8

The reason: This is done in order to fulfill his obligation of Kiddush Bemakom Seuda even according to those who hold that a single Revius of Kiddush does not suffice for this purpose. [Admur ibid]

[6] See Admur ibid; M”A 273:13; Birkeiy Yosef, brought in Shaareiy Teshuvah 273:7