Crabgrass pre-emergent products need to be applied within a strict time window, and that time frame is ending within a day or two. If you want to prevent crabgrass, this should be your first action. The University of Minnesota recommends that chemical treatment of lawn weeds take place in the fall. You can hand dig them at any time. See this link for specific information about lawn weeds and their treatment: https://extension.umn.edu/lawn-care/lawn-weeds#application-timing-1536713