There are theoretical arguments and empirical studies to support the benefits of early participation in an online course. However, little research has been conducted to investigate the relationship between students' early start in online learning and their course performance, which limits its application to online education research and practice. This study aims to fill this gap by examining and quantifying the relationship of early participation in course activities with students' learning performance. Using multilevel logit modeling, the relationship of early participation in online courses and student final performance are modeled with student log data and other individual information from over 30,000 students enrolled in 22 online university courses. Results show that early participation in online course activities is significantly correlated with student final performance. As the first study to quantify the relationship between early participation and students' academic performance, this paper provides important insights for online teaching and learning research.