Consumers often spend time searching before making a purchasing decision to acquire knowledge about products. If the purchasing decision is delayed, recall of acquired knowledge is likely to be impaired. Because products in the marketplace are rarely described completely, consumers who take too long to decide may fail to notice the absence of information relevant to a purchasing decision and fall prey to a phenomenon called ‘omission neglect’, an inability to detect missing information and form extreme and confidently held judgments. Omission neglect may be corrected by acquiring knowledge about the target product before making the choice. In the present research, we examine consumer decisions in the context of choice sets described incompletely and presented either immediately or a week after the acquisition of relevant information about a target product. Specifically, we investigate how the timing between product knowledge acquisition and decision-making affects the detection of missing information, decision confidence, and choice deferral. Across three experiments, we find that, after acquiring knowledge, when consumers have their decision delayed, they are less able to detect missing information, feel more confident, and defer choices less.