We examine the impact of credit mobility exchange programs' timing on students' academic performance, focusing on the moment in which students travel and the length of the period spent abroad. To provide causal evidence, we exploit unique data from more than 10,000 students from a well-known and internationalized Brazilian university from 2010 to 2020. By combing Propensity Score Matching with Difference in Differences techniques, we find that international mobility impacts groups of students differently. Students who travel closer to the end of their undergraduate courses benefit the most from the mobility experience, while negative effects are found for those who travel at the beginning of their university program. Results also show that, while student mobility impacts positively and significantly students who participate in programs lasting from one semester to 1 year, negative effects are associated with shorter periods abroad. Our findings also reveal heterogeneity across destination countries. Mobility has a positive impact on students' grades for those students traveling to English-speaking countries. Our analysis presents empirical evidence that can be used to design international student mobility programs, providing insights to policymakers engaged in maximizing their effects.