Period start and end date (Copper IUD spotting)

katya
Hey, 
I'm not sure when to consider my period start and end date. I tend to spot some beforehand since I got my copper IUD (seperate topic and question, I guess). However, I've always considered my first day of my period to be light which confuses me now because I don't know if the day I think I'm spotting is just a light period  day or doesn't count at all? Also would my end date be the last day of bleeding (some blood or spotting) or the day after? 
Also how long did it take for you to stop spotting from your Copper IUD if you have one? 
Sorry if this doesn't make a lot of sense