Logging period correctly in glow?

This may be a dumb question... I really want to log everything correctly in this app to get the most accurate results. What day do you put for the “end” of your period? My heavy flow/cramps/backache usually stops after 4 days but I still wear a liner and have some light bleeding for like 3 days after. So I’m not sure what day is the “end” of my period.