NuvaRing

I’ve been using a nuvaring for a few months now, since April or May. I was told by my doctor to leave it in for 20 days and put a new one in after a week (you know, 7 days lol). Sorry to sound stupid, but I read the instructions that said to leave it in for a full 3 weeks (21 days). Could the one day difference affect the effectiveness of the ring?