To overcome resource constraints and achieve exponential growth, a new venture must rely on early customers of its products to communicate value and commitment to others. For this reason, founders of new ventures focus more on early customers as a key element of their founding strategy than on other elements. But when do early customers really add value to new ventures? Scholars have used legitimacy theory to examine the benefits of gaining acceptance and conveying firm quality through conforming to social norms and following similar methods and forms. It has been argued that, independent of the customers of products and services, observable legitimacy characteristics of a new organization function as signals and are used by critical external constituents to infer the quality of the firm. This research, however, sheds little light on the manner in which firm legitimacy influences how potential customers respond to the existence of early customers. The current study therefore proposes that, depending on types of legitimacy (cognitive, regulative, and normative), early customers may have a different impact on subsequent firm performance. While a young firm may reduce information asymmetry that hampers their attractiveness to customers and other external stakeholders via the costly signal of obtaining early customers, the signal fit argument suggests that discrepancy between a signal and the characteristics of the signaler can lead to unreliable quality and lower signaling value. Legitimacy is critical because, when legitimacy is absent, early customers may not serve as an effective signal for the new venture. This study therefore explores the extent to which the signaling effect of early customers depends on these three types of legitimacy. This study employs the Kauffman Firm Survey (KFS) public database, a panel study of 4928 new businesses founded in the United States in 2004. Four surveys (baseline, first follow‐up, second follow‐up, and third follow‐up) were conducted using self‐administered Web survey and computer‐assisted telephone interview methods. In this study, the independent variables include early customers and the three types of legitimacy (cognitive, regulative, and normative) as well as a set of control variables. All independent variables were measured at the founding of the businesses in the KFS baseline survey. Dependent variables in this study include second‐year revenue, third‐year revenue, and fourth‐year revenue as measured in the KFS first, second, and third follow‐up surveys, respectively. The multinomial logistic regression and Heckman sample selection model is used to analyze the data. Results show that early customers are beneficial to new ventures, and the benefits of early customers to firm performance are higher when there is cognitive legitimacy from a capable founding team and regulative legitimacy from paying federal Social Security and Medicare taxes. Surprisingly, while incorporation improves performance for new ventures, the benefit of having early customers relative to not having early customers is lower, not higher, when the firm is incorporated than when the firm is not incorporated. Early customers have the same benefit regardless of the presence of normative legitimacy through the presence of a network with suppliers. This study therefore offers insights into the role of early customers at founding. Early customers can be very useful for founders with significant experience, and it may be a good strategy to seek them out. However, it appears that there are specific conditions under which pursuing early customers may not be an effective strategy. Founders can make strategic decisions not to pursue early customers if there are no anticipated payoffs.