Water lawns to be serviced, for a period of (15) minutes the evening before service. Remember (15) minutes is plenty. In this case less is more. An over watered lawn makes it difficult to aerate a lawn properly. If your timer is set to water in the morning, that's ok too.
Water for the next (2) days after service. This facilitates the introduction of nutrients into the root system, creating a healthier, greener, thicker looking lawn.