It is possible, yes. With
NuvaRing, you need to use condoms
for a month
for it to be fully effective. However, you are definitely playing with fire. It makes no difference if you ovulate a few days later, as sperm last 5 days on average in the female body and 7 in perfect conditions. While calenders are helpful, they are by no means exact. It's safer to assume there is no safe time. You need to wait 2 weeks and take a pregnancy test with first morning urine.