The regulation of growth, aging, and lifespan share fundamental genetic and metabolic pathways. An unsolved problem for growth regulation is understanding the mechanisms through which cells, or groups of cells, coordinate when to initiate a new phase of growth, such as puberty. Here, we propose a novel mechanism called decentralized cellular time-keeping as a method by which an individual cell, as part of a network of cells, can estimate the age of the network. Decentralized timekeeping is based on a cell mapping increasing information entropy in intercellular communication to organism age. We demonstrate with a computational simulation how such a system could regulate growth.