Should I tell my boyfriend's sister I nicked her car's bumper immediately or wait?

Asked by chelle21689 (7907) September 6th, 2014 from iPhone

I was parking behind my boyfriend’s sister on the driveway and I was even trying to be really careful. My boyfriend walked out and noticed my car was touching her part of the car where there is that black plastic trim that isn’t part of the paint job. I backed out away and noticed there were some light surface scratches but I could easily wipe it away. I didn’t even know I hit it cuz there was no bump felt or even heard.

Then I noticed a tiny nick, smaller than half a dime. Hard to notice unless you sit there close up and inspect it and look towards the bottom of the bumper and tilt your head.

I’m not sure whether to tell her ASAP when I first see her when she comes back from vacation today OR wait to see if she even notices. My bf said she might notice because she’s loves her car and notices everything.

I’m not sure what to do but I feel bad. I was going to tell her either way but I’m not sure if I should just tell her right away if she’s not going to notice..