When does a distinguishing discharge (Tamyeed) necessitate abstaining from prayer for a woman?

Primary text

If a discharge is distinguishable (Mumayyizah), abstention from prayer is required immediately upon recognizing the distinction, without the need for repetition. This view is supported by the apparent statement of Al-Khiraqi and what is narrated from Ahmad, as well as the opinion of Ibn Aqil. The reasoning is that the essence of distinction is discerning one blood from another in attribute, which is achieved upon the first instance. Al-Shafi'i holds this position. The evidence is the Prophet's saying: 'When menstruation approaches, stop praying, and when it departs, wash the blood off yourself and pray.' This commands cessation upon approach without further stipulation, extending until its departure, and distinction itself is a sufficient sign, requiring no addition like established custom.