Is it permissible for my wife to purify herself after 27 days following a Caesarean section and the cessation of bleeding, or must she wait for 40 days?

If a woman gives birth, whether naturally or via C-section, the blood she sees in connection with the childbirth is post-natal bleeding (nifas), which prohibits prayer, fasting, and intercourse. If the bleeding stops and she sees one of the two signs of purity (dryness or white discharge) before forty days, she has become pure and must perform ghusl (ritual bath), after which she can pray, fast, and have intercourse. If the bleeding does not stop, the nifas continues until the completion of forty days.