Tracking AF

Curious, when tracking AF do you track as soon as there is a change in colour of dicharge? May sound silly just want to make sure I’m tracking accurately. For instance do I track AF as soon as I get dark discharge (brown old blood) keep tracking as it changes to red, then back to brown? I would assume so just wanting to be sure I have Been tracking accurately ! And then finish tracking once it is back to normal discharge / CM?