Shemona Yemei Mila

In the Piyut of Echod Mi Yodea it says Shemoinoh Yemei Milah

eight days of Milah (based on the gemoro Eruvin 40b)

The meforshim ask , There is only one day of Milah on

the eight day, and  not eight days of Milah.

I heard an answer given by R. Chaim Kanievsky Shlita.

There is an obligation not to make a Bris before

the eight day.*

Therefore there are eight days of Milah .

The first seven days to make sure not to do

the Bris and on the eight day to do it.

*many poskim hold that you weren’t  yotzei mitzvahs milah