Unfortunately it can be difficult to distinguish between heavy staining and a light flow. There is no specific guideline or quantity of blood to determine whether one is experiencing staining or a flow. One possible (but not set in stone) guideline is that if the bleeding is too heavy to be contained by a pantyliner, and a woman needs to use more significant protection such as a pad, that is likely a flow. For more detailed discussion, please see our video on this topic and our page on stains.
While you are staining, we recommend abstaining from intercourse, but other forms of physical contact are permitted. You are not required to check regularly to see whether the staining is turning into a flow. If the staining takes place around the time you expect your period, it does make sense to check (once or twice a day, or when you go to the bathroom) to see whether it has become a flow. If the staining comes at a time you are not expecting your period (and may or may not turn into a flow) you need not check specifically, and may take precautions against becoming niddah from the staining unless it turns into a flow. See our page on stains for further details.
Vesatot are calculated from the onset of the flow, even if you were rendered niddah earlier from staining. Therefore, this initial staining does not affect your veset calculations. If you are unsure when the staining definitely turned into a flow, you would calculate your vesatot next month from the earliest point that you are certain you had a flow (even if it might have begun earlier).
Please feel free to get back to us with any further questions.
B’Hatzlacha!