Diachronic word embeddings offer remarkable insights into the evolution of language and provide a tool for quantifying socio-cultural change. However, while this method identifies words that have semantically shifted, it studies them in isolation; it does not facilitate the discovery of documents that lead or lag with respect to specific semantic innovations. In this paper, we propose a method to quantify the degree of semantic progressiveness in each usage. These usages can be aggregated to obtain scores for each document. We analyze two large collections of documents, representing legal opinions and scientific articles. Documents that are predicted to be semantically progressive receive a larger number of citations, indicating that they are especially influential. Our work thus provides a new technique for identifying lexical semantic leaders and demonstrates a new link between early adoption and influence in a citation network.