Start it again and kill the engine if you don't get oil pressure within 10 seconds max. Hopefully the engine is still well lubricated. That is why you really dont want to do overnight oil changes because the residual coating of oil in the engine will eventually drain off and that first startup would be very stressful for the engine. You could open the oil filter cannister again to make sure everything is in order but I think that you didn't let the engine run enough. The metal ring is a crush washer that you should have replaced; but it wouldnt cause no oil pressure. Another scenario is that your oil pressure sender broke (common problem on the engines) but first see if it you get any oil pressure after 10s.