New lawn so far
Seesded 9/1. Germinated approximately 9/8. Long, wide shot of grass looks great so far in photo 1. But looking straight down, there are many of the weed In photo 2. What is it? Can I handle it now? In photo 3, top right corner is much sparser, probably due to runoff. Should I reseed now?? Finally, should I really be stepping on the grass to put down Nitrogen? In case it's not obvious , I'm a big worrier and want to get this right!
We viewed your photos. The weed looks like chickweed. There must have been a large seed bank in the soil. This may take several seasons to get under control.
We also see in your photo a downspout that goes underground. Looks like you have some erosion on that side of the house. The soil looks wet and we see mulch/grass in that area. Correct the drainage in that area to redirect the moisture or you may continue to have an issue.
You will have to control the chickweed in the spring. You can apply a preemergent in the late summer/early fall around Labor Day next season to prevent germination of chickweed.http://extension.umd.edu/hgic/common-chickweed
Now you may be able to handpull some of the worst weeds in small areas. Reseed bare areas around the beginning of October. You should be able to walk on the new seedlings then. You can fertilize at the same time you seed. See our fertilizer schedule http://extension.umd.edu/hgic/umd-extension-lawn-fertilizer-schedule-home-lawns
In the third photo we notice chickweed possibly on your neighbor's side. You may want to convert the area on your property line to an ornamental landscape bed. You can look for plants that tolerate moisture. Also, it will be much easier to handpull chickweed in landscape beds than a lawn.