I doubt you did any damage at all if it only ran for 30 seconds. 500 miles would be plenty soon enough for the oil change. I think you meant seat the rings. Don't drive at a constant speed for the first couple hundred miles. Also, run the car at fairly low rpm and hold the throttle wide open until you get up to 50 mph or so. Do this every so often and the rings should be seated. I can't really say how many times is necessary but if you do it more often it won't hurt anything.