In coalition governments, ministers' agenda-setting power depends on their coalition partners. A minister facing a cooperative partner is less constrained than a minister facing a competitive partner. While ministers may not know their partner's type at the beginning of a government's term, in this study we theorize that, over the term, ministers form and update their beliefs about the competitive or cooperative type of their partners after observing the level of scrutiny of their bill proposals, and respond by strategically timing their subsequent bills. We derive this implication theoretically, through the development of a dynamic model on the timing of ministerial bill initiation, and demonstrate it empirically, from data on bill initiatives from 11 parliamentary democracies. Our results demonstrate that a minister strategically delays bill introduction the more she experiences scrutiny, the more her partner has policy incentives to scrutinize her bills, and the less power she has to constrain scrutiny in parliament. These findings further our understanding of legislative efficiency in coalition governments and why governments quickly adopt or delay policy reforms demanded by voters.