It is customary for the Bris to be performed in a synagogue. If this is not possible, it can be performed at home or in any other fitting location. It is preferable for the Bris to be performed in the presence of a Minyan (a quorum of ten Jewish male adults over the age of thirteen), for we are taught that when ten Jewish men are gathered the Divine Presence rests on the assemblage in an amplified manner.
Time of Day
A Bris is usually performed following the Morning Prayer service. If this is not possible, it can be done any time during the day. However, a Bris can never be done at night, which according to the Jewish calendar, begins at sunset.
If having the Bris in the afternoon will result in a larger attendance, it is preferable to wait and have it done in the afternoon, as this adds in the joy of the mitzvah.
Causes for Postponement
It is of utmost importance that the Bris be held on the eight day from the child’s birth. However, in certain medical circumstances where there is even a remote possibility that the child is not strong enough to undergo the Bris, the Torah requires that the Bris be postponed until he regains his strength.
Also, when the child has a yellow appearance and has been diagnosed with jaundice, we must wait for the condition to clear and perform the Bris on the following day. However, in certain cases we even wait an additional seven days before performing the Bris, as Maimonides states: “It is always possible to perform a Bris, whereas one cannot bring a Jewish soul back to life.”
In the case where there are twins (or more), and one is healthy and can undergo the Bris, while the other is not, we make each Bris separately and do not wait to do them both at the same time. One should consult a competent Rabbi or Mohel to discuss any circumstances that may deem a postponement.
A Bris on Shabbat
If following a natural delivery (to exclude caesarean births) the Bris falls out on Shabbat, all preparations for the Bris must be done prior to the onset of Shabbat (which begins with sunset on Friday). One should consult a competent Rabbi for the proper procedures.
A Bris on Special Days
Rosh Hashanah: The Bris is performed following the Torah reading of the morning services, before the sounding of the Shofar.
Yom Kippur: The Bris is performed following the Torah reading of the morning services. The celebratory meal is held at night, after the fast is over.
Sukkot: The Bris is performed in the usual time, but not in the Sukkah. However, the celebratory meal is held in the Sukkah.
Purim: The Bris is performed following the Torah reading of the morning services, but before the reading of the Megillah. If it is performed at home it is done after the reading of the Megillah.
Tisha B’Av: The Bris is performed following the recitation of the Kinot. The celebratory meal is held at night, after the fast is over.
(Content courtesy of www.circumcision.net)