“Readiness cohorts” are an innovation in clinical trial design to tackle the scarcity of time and people in drug studies. This has emerged in response to the challenges of recruiting the “right” research participants at the “right time” in the context of precision medicine. In this paper, we consider how the achievement of “readiness” aligns temporalities, biologies, and market processes of pharmaceutical innovation: how the promise of “willing bodies” in research emerges in relation to intertwined economic and biological time imperatives. (...) Drawing on long-term engagement with the field of Alzheimer’s disease prevention and interviews with researchers from academia and the pharmaceutical industry, we describe the discursive construction and practical arrangement of readiness. This paper contributes to understandings of temporal specificity, or “timing,” within prevention research and casts critical light on the way this specificity—the threshold for “trial readiness”—relates to an opaque and highly speculative drug development pipeline. Extending the study of biomedical potential, as that which holds promise but may not yet exist, we consider how absences operate in adaptive trials. By highlighting these absences, we outline an opportunity for socio-ethical research to intervene in the speculative gaps of drug development. (shrink)