How Many Days of Waiting Are Required Before a Hefsek Taharah?

Greetings and blessings,

The view of Maran Rabbeinu Ovadia Yosef ZTL in his work Taharat HaBayit (vol. 1, p. 396), is that one should wait 72 hours from the time of marital relations, and then a hefsek taharah may already be performed. This is called waiting 4 days, because 72 hours usually end in the middle of the night, and a hefsek taharah cannot be performed until the following day, close to sunset. And the custom of Ashkenazim is to wait one additional day beyond what we wrote. There is no need at all to be stringent and wait additional days, as Maran wrote: "The lenient one is rewarded, for he hastens with him to a mitzvah."

With blessings,
Menashe Ben Porat