After Hazrat Safiyya (r.a) was taken captive in the Battle of Khaybar, the Prophet manumitted her and married her. But, in accordance with the practice of istibra, he didn't consummate his marriage till she was free from menses (hadith). Its also mentioned that between Khaybar and Medina, the Prophet stayed for 3 days, between which the marriage was consummated (hadith).
From these, it means that the iddah of Hazrat Safiyya (r.a) was for a approximately 3 days, although it can be a little more because after taking her as captive, the Prophet may have stayed for a small time in Khaybar. So, what could be the approximate (or exact) idda period of Hazrat Safiyya ?