This makes sense and is probably the way I will go. Pump up sprayer and spot mist just the weeds. Should be good to seed within two weeks.The biggest concern is whether or not you’re using low volume out of a machine or dragging a hose and flooding the lawn with 2 to 3 gallons of liquid per thousand square feet. Low-volume means you’re getting more product just on the leaf surface and not the soil, where as a hose end sprayer means you’re getting more not only on the leaf surface but obviously the soil as well.
It is the soil that you have to be concerned with in making sure the product has moved out of it so you would then be able to seed. Most manufacturers will tell you to wait 2 to 3 weeks to be safe.
On the other hand, I use low volume when spraying weeds. I have typically only waited a week to 10 days maximum before seeding just to make sure the weeds have died. And if I’m only needing to spot spray, I will spot spray the few weeds and seed right then and there.