I’ve had several of these questions as well but the first came from Andrew Hardesty so let's blame this part on him. Generally, I use a crab grass prevention product in the first spray. Crab grass, as you may remember, is an annual, meaning it grows from a seed each spring. This product is not smart enough to know good grass seeds from crabgrass seeds. If you seed before I spray, it will keep both seeds from germinating. That’s not the result either of us want so what’s the better answer?
After I spray, give it a good couple of rains not on the same day and then follow this procedure. Use a garden weasel, or a shovel to break up the surface of the soil. My treatment is a chemical barrier that does not allow the tap root to be successful but if you rough up the soil, The chemical barrier is defeated and your grass seed stands a better chance. Yes, you will also have crabgrass in these areas but that’s something I have tools to deal with in the summer.