In research practice, it is common to measure cognitive load after learning using self-report scales. This approach can be considered risky because it is unclear on what basis learners assess cognitive load, particularly when the learning material contains varying levels of complexity. This raises questions that have yet to be answered by educational psychology research: Does measuring cognitive load during and after learning lead to comparable assessments of cognitive load depending on the sequence of complexity? Do learners rely on their first or last impression of complexity of a learning material when reporting the cognitive load of the entire learning material after learning? To address these issues, three learning units were created, differing in terms of intrinsic cognitive load (low, medium, or high complexity) as verified by a pre-study (N = 67). In the main-study (N = 100), the three learning units were studied in two sequences (increasing vs. decreasing complexity) and learners were asked to report cognitive load after each learning unit and after learning as an overall assessment. The results demonstrated that the first impression of complexity is the most accurate predictor of the overall cognitive load associated with the learning material, indicating a primacy effect. This finding contrasts with previous studies on problem-solving tasks, which have identified the most complex task as the primary determinant of the overall assessment. This study suggests that, during learning, the assessment of the overall cognitive load is influenced primarily by the timing of measurement.