How to Count Seven Days for Sheva Brachos?

Does the Chupah Count as Day One of Sheva Brachos?

The week of the wedding—the shivas yemei hamishteh (seven days of festivity)—is marked by special seudos (feasts) of celebration which culminate (under certain conditions) in Sheva Brachos, the recital of seven special blessings relating to marriage.

If the chupah—which is the crucial part of the marriage ceremony—takes place by day, that day serves as the first of the seven days when Sheva Brachos may be recited, and the ensuing night is then counted as the beginning of the second day. (Due to the doubt surrounding the status of the time of bein hashmashos (twilight), between shkiah (sunset) and tzeis hakochavim (emergence of three stars), we are stringent and consider it in this regard as day.)

However, what must take place before tzeis hakochavim for the chupah to be counted as day one is debated among poskim: some say it’s enough if the chupah was erected before tzeis hakochavim, others say that the last brachah of the Sheva Brachos recited under the chupah must have concluded before that time, while still others maintain that the newlywed couple must have left the yichud room by then.

The consensus appears to be the middle view, namely, that if all of the Sheva Brachos recited under the chupah were completed while it was still day, that day counts as day one and day two begins immediately at nightfall. 

A practical example: if the chupah takes places on a Monday afternoon, and the last brachah was recited before tzeis hakochavim, the shivas yemei hamishteh begin on Monday and are celebrated until the following Sunday afternoon. Sheva Brachos would no longer be recited at a meal taking place on Sunday night following the wedding. But if the last brachah under the chupah was recited Monday after nightfall, then Tuesday would be considered day one and Sheva Brachos may be recited until the following Monday afternoon. 

However, for other matters, such as not reciting tachnun (prayers of supplication following Shemoneh Esrei), the seven days are counted me’es l’es (as complete 24 hour periods). Therefore, the seven days come to an end a week later, at the exact time that the chupah took place. #459

https://halacha2go.com?number=459

Practical Halacha: One minute a day. By Horav Yosef Yeshaya Braun, shlita, Mara D'asra and member of the Badatz of Crown Heights.