Progress updates indicating that the implementation of agreed actions is on track (option B) would best guide an IS auditor when determining an appropriate time to schedule the follow-up of agreed corrective actions for reported audit issues. This option suggests that the corrective actions are being implemented as planned and that there is evidence of progress toward addressing the identified audit issues. By ensuring that the implementation is on track, the auditor can schedule follow-up at a suitable time to verify completion and effectiveness. While other options may also provide relevant information, such as sufficient time elapsed since implementation to provide evidence of control operation (option C), progress updates indicating implementation progress offer more specific guidance on the timing of follow-up activities. Option C focuses on the passage of time rather than active progress toward resolution.