During the past 5 years, electrification in Kenya has grown by more than 30% due primarily to increases in grid penetration and solar home systems. This represents a way forward for governments, international finance institutions, and entrepreneurs to address some of the challenges of energy access. However, little is understood about how consumption has evolved among these newly-electrified customers. In this paper, we address this by conducting a longitudinal analysis for 136k utility customers across Kenya over six years of electricity bills, uncovering critical trends in spatio-temporal evolution of electricity consumption. Our analysis reveals that recently-electrified customers are reaching their steady-state consumption more quickly than previous customers, that the steady-state is increasingly less, and that typical urban and peri-urban customers tend to consume 50% more electricity than rural customers. In addition we present implications for policymakers and electricity planners considering grid extension and distributed systems for improving electrification.