There is no fixed standard for how many days of delayed menstruation during lactation is considered normal, as each woman's physical condition and hormone level recovery rate vary.
Generally speaking, if the menstrual cycle is regular before lactation, delaying menstruation by one week during lactation may be within the normal range.
However, some women may experience delays or irregularities throughout their menstrual cycle during lactation, which is a normal physiological phenomenon. If the delay is too long or there are other discomfort symptoms, it is recommended to consult a doctor.