How Long Does It Take For Dicynone To Stop Light Bleeding In A Pre-teenager With Prolonged Periods?

My daughter is 12 years old. She got her periods on october 29th and its still continuing. Though there is no heavy flow she still has light bleeding. Started taking Dicynone 2 days back as per doctor s advice. But light bleeding is still there. How long after starting this medication does periods stop completely? (Her first periods was on January 9, 2023. )