Checking the backup job completion notifications or logs is the first action you should take to verify that the automated backups are completed successfully. Logs and notifications provide immediate feedback on the job's outcome and will alert administrators to any errors or failures that occurred during the backup process. Examining the size of the backup compared to previous backups can provide additional context but it is a secondary step that typically follows an initial check for job completion or failure notifications. Manually reviewing files in backup storage could further validate the completeness of backup, but it's not efficient as a first step. Projecting future storage needs based on success of backups is a planning activity and does not directly address whether the backups have completed successfully.