Infrastructure has long been understood as central to enabling “progress”, a visible sign of modernity and development. Urban scholars have pushed back against modernist notions of the networked city as the teleological end of infrastructure, yet there remains uncertainty and debate over how to make sense of infrastructure’s temporality. We emphasize that – analytically – infrastructure is always “in formation”. To understand infrastructure’s politics, we consider how progress and completion are narrated, imagined, adjusted to and politicized by providing three contrasting infrastructure vignettes in Nairobi. In our analysis of a bus rapid transit system, we see incremental changes and proclamation of an envisioned final state. In our consideration of the laying of pipes, wires and sidewalks, we see acceptance of what are seemingly indefinite disruptions and politicians wanting to be associated – for as long as possible – with the building of infrastructure. Finally, we examine sanitation infrastructure, where particular toilets may be “complete” but their connections to elsewhere remain in flux and future configurations remain ambiguous. We conclude by reflecting on the politics of the temporality of infrastructure, and the ongoing significance of “making progress” and the possibility of completion for the kinds of infrastructure that are imagined, funded, built and supported.