Nuvaring

I put my nuvaring in a couple days after my period. Let's say it was a Friday. I keep it in for three fridays and on that third I take it out, correct? And because I prefer to have a period, I wait a week and then put a new one in on the fourth friday, correct? Same time I put my first one in, right? 

I'm sorry if that's so confusing, but I'm very confused! And I don't want to take any chances. 

Thank you in advance!