‘Acceleration’, that is, the performance of activities in ever-shorter periods of time, is a distinctive feature of contemporary organizations and societies that is reflected in, and driven by startups’ attempts to scale up their businesses in ever-faster ways. Although prior research has highlighted that temporary organizing is a key way to accelerate the startup process, little is known about how actors do so. Based on a one-year ethnographic study at a startup accelerator, the authors explore how actors enact temporary organizing to attempt to accelerate the startup process. Their analysis shows that this process involves a plurality of partly conflicting temporal structures. As their study shows, such conflicts invoke tensions that actors live out in their daily activities. The authors identify three temporal practices – sequencing, freezing, and merging – through which actors engaged in temporary organizing enact acceleration in the startup process by reconciling these temporal structures. Their study has implications for understanding time in the expanding literature on temporary organizing and acceleration.