I have cenepede grass in my yard, what is the best time to use the halts crabgrass 0n the yard

Scotts Halts Crabgrass & Grassy Weed Preventer will prevent crabgrass and other grassy weeds from growing. It will not kill or control broad leaf weeds such as clover. To prevent crabgrass the application is best done in the early spring, before temperatures are consistently in the 80's. If there have been four consecutive days with temperatures of 80 degrees or above, then it is typically too late to apply as the crabgrass has already germinated.