In next-generation Passive Optical Networks (PONs), the traffic exchanged among Optical Network Units (ONUs) belonging to the same PON, i.e. inter-ONU traffic, will increase because of emerging applications and services such as the smart grid. Applying Network Coding (NC) techniques to the inter-ONU traffic will improve throughput, security and reliability. However, the implementation of NC causes additional queuing delay at the Optical Line Terminal (OLT), and degrades the fairness among coded and un-coded inter-ONU flows in terms of latency. This paper proposes a novel bandwidth scheduling technique, i.e. a Grouped Random Scheduling (GRS) algorithm, to reduce the additional queuing delay at the OLT.