Defect prevention should be initiated during the

Defect prevention should be initiated during the requirements phase. This phase is critical because:

Early Detection:Identifying and addressing defects early in the requirements phase can prevent downstream defects in design, coding, and testing phases.

Cost Efficiency:Defects found later in the project lifecycle are more expensive to fix than those found early.

References:

Software Engineering: A Practitioner's Approach by Roger S. Pressman

IEEE Standard for Software Reviews and Audits