Division of labor (DOL) is a principal characteristic of workers in mature colonies of many social insect species. In newly initiated ant colonies, however, the first workers (called nanitics) are few in number and much smaller in size than workers of mature colonies. This limited workforce must nevertheless perform most of the tasks of a mature colony, and it is unknown if they also exhibit DOL. In this study, we tracked several inside-nest and outside-nest behaviors of nanitics in incipient Pogonomyrmex rugosus colonies. We found that a clear age-based DOL arises in these colonies, where the oldest worker (even if only by a few hours) is biased towards foraging, while younger nanitics concentrate on brood care. Transitions by individuals across tasks occur more often when pushed (i.e., the eclosion of new nanitics into the brood care niche causes existing nurses to shift towards foraging) than when pulled (i.e., forager deaths do not quickly shift nurses into an empty foraging task niche). The overall similarity in DOL across incipient to mature colonies suggests that all workers in P. rugosus follow a relatively consistent developmental ontogeny, regardless of the immediate circumstance and condition of the colony. Nanitics may, however, be unique in how rapidly they progress through their age-based behavioral repertoires.