possible pregnancy?? HELP!

So hubby and I decided to do the do. Well we did so on the last day of my period.. I've had it for, today being the 5th day, and it was soooo light a pantiliner was sufficient enough the entire time when normally I have to use extra absorbent because I bleed so heavy.. 
ANYWAYS we had sex and he came inside me, I immediately inserted my Nuva Ring (I know I should've done it beforehand but I wasn't thinking) what are the odds this can lead to pregnancy ??