With the rapid implementation of early foreign language programmes in the state of North-Rhine-Westphalia, Germany, first for Grade 3 (ages 8-9 years) in 2003 and then from Grade 1 (ages 6-7 years) in 2008, primary school teachers had to adapt to teaching a foreign language in Grade 1 quickly. Teachers had little experience with language teaching to very young learners, and curricula and materials had not been tested prior to implementation. This study investigates the development of receptive English proficiency across three large cohorts (N = 7,289). The first cohort started in Grade 3, the second cohort was the first to start in Grade 1, and the third cohort started in Grade 1, six years after the initial implementation. Propensity scores were used to compare sampling weights of cohorts without the influence of confounding variables. Results confirmed a slight advantage for an earlier start in primary school for students' receptive proficiency in Grade 5. The results further indicate that proficiency scores did not improve from the first cohort of students starting in Grade 1 to one six years later. Systemic changes in teacher education for language specialists in primary education may not yet have been able to affect student outcomes.