Purity: Waiting for Bleeding to Stop
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 408:
If a mustaḥāḍah knows that before the end of the time for prayers her istiḥāḍah will completely stop or that it will stop for long enough for her to perform prayers, then based on obligatory precaution, she must wait and perform prayers when her istiḥāḍah has stopped.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)