Common practice when a woman has a stained bedikah, even one that comes shortly before a flow, is to calculate vesatot only based on the onset of flow. However, this case is slightly different, because your bedikah was on your onat haveset, shortly before the flow began.

For this coming cycle, you should calculate and observe vesatot based on your flow at night, as usual. In addition, during the preceding onah, you should pay attention to premenstrual symptoms or staining, and abstain accordingly.