An IS auditor reviews a company's backup strategy for a critical transactional database. The organization performs a full backup every Sunday and synthetic full backups are not used; instead, transaction log backups are taken every 15 minutes throughout the week. During a test, the DBA restores the database to the state it was in on Wednesday at 2:00 p.m. Which of the following is the MOST important factor determining whether this point-in-time recovery will succeed?