It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both): If a woman becomes pure during the time of the Asr prayer, she should begin with Zuhr and pray it first, then pray Asr; and if she becomes pure during the time of Isha, she should first pray Maghrib, then pray the Isha prayer.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1816