Well without seeing the location it's hard to say, but 4 days is really not enough to tell what's going to happen. After 10 days, you should have a much better idea if it will come in thickly enough. If not, you can reseed the open areas, but be aware that no matter where you live, turf grasses of all types do best with a spring or fall start. June is not the best time to try to get a lawn started from seed. Be sure to keep the area slightly moist at all times to help germination.