How Early Will Walgreens Refill A Prescription? (2022 Guide) Walgreens, America’s biggest drugstore chain, offers convenient services that allow customers to refill their prescriptions on a regular basis. Some times you will need your prescription refill sooner than planned. Here is what I’ve found through my research! Is it possible for Walgreens to refill prescriptions as early as 24 hours? Walgreens must refill your prescription 3 days before due date for Schedule III/IV drugs. Schedule II (controlled) substances require a new prescription for every refill. Walgreens will adhere to the refill schedule as well as any limits set by your…