What time of day is best to do the bris?
A bris can be performed any time during daylight hours on the 8th day, or after the 8th day if it's delayed for health reasons. The best time of day, though, is early in the day, just after morning shacharis services. This is because it is best not to delay doing a mitzvah whose time has come. Also, kabbalistically, the orlah (foreskin) should be removed early on the day of the bris, before negative impulses can enter the baby.
If it is a regular business day (Monday, Wednesday, Thursday, or Friday) for Dr. Katz, he is generally available to perform your son's bris either in the early morning (approx. 8:00 AM) or at lunch time. During summer months, when it stays light later, he is also available in the early evening, approximately 6:00 PM.
Please speak with Dr. Katz directly to work out exact times for your son's bris. Call him as soon as possible after your child is born, as others may be scheduling brises for the same day as your son's.