Depending on the type of slit seeding you are doing then there are two wayus to appraoch it. If you are doing spots throughout the yard and no real large open areas then the the product Drive can be ued and does well for spot treating of crabgrass once it has emerged. If you are doing large open areas with plenty of sunlight , then you are probably better to use the Tupersan. Personal preference is to use the Drive because will attempt to fill in at different times and the control with Tupersan will disipate quickly 2-4 weeks depending on moisture and photodegradation. Best to seed early either way so grass can get the time to compete before summer comes in. Being where you are crabgrass probably isn't an issue until late May!