On my wing kit (circa 2007) the #8 holes are countersunk not dimpled. Unless that has changed you have the wrong nutplate in hand. There is probably enough room to drill the correct hole to #19 and rivet the nutplate on with only one rivet. After drilling and countersinking the correct hole I think the holes will be close but you will be fine. The single rivet only has to hold it in place long enough to start tightening the countersunk screw for the wing root fairing. The wing root fairing is pre punched so you need the #19 hole to line up correctly. In the picture below I'm holding a #19 bit next to the hole you accidentally drilled.
If you are really paranoid back all the holes with a doubler strip and match drill all holes accept the #19. You should be able to rivet that inner nutplate rivet hole to the doubler then rivet the doubler and nutplate through the other holes.