A method, system, and computer program product for ordering grants of upstream bandwidth in a two-way grant-based communication system, such as a DOCSIS-based communication system. Typically, a central controller, such as a CMTS, sends a grant message to a set of end user devices, e.g., cable modems, wherein the message defines when each end user device can transmit upstream. The invention first determines, for each end user device, the time needed for processing the grant message. The central controller then constructs the grant message, such that grants for the end user devices associated with the shortest grant message processing times occur early in the grant message and represent the earliest grants. Grants for end user devices associated with the longest grant message processing times occur later in the grant message and represent later grants. With this ordering of grants within the grant message, the CMTS can assume a smaller processing time for processing the grant message by CMs, such that the grant message does not have to be sent so far in advance. Performance of the system is increased due to decreased roundtrip delay.