Mastering a katana, or any martial art or weapon, is a lifelong journey that requires continuous dedication, practice, and learning. Becoming a true master of the katana is a long-term commitment, and the time it takes to reach a high level of skill and expertise can vary greatly depending on several factors:

1. Frequency and intensity of training: The more frequently and consistently one trains with the katana, the faster they are likely to progress. Regular, focused practice is essential for developing muscle memory, refining technique, and improving overall proficiency.
2. Quality of instruction: Having a skilled and knowledgeable instructor who can provide guidance, correction, and advanced training methods is invaluable for progress. The expertise of the instructor and their teaching methods can significantly impact the learning process.
3. Individual aptitude and physical abilities: Each individual has unique physical attributes, coordination, and learning capabilities. Some may naturally excel in certain aspects of swordsmanship, while others may require more time and effort to develop proficiency. However, consistent effort and a growth mindset can overcome inherent limitations.
4. Experience in related disciplines: Prior experience in martial arts or other sword-related disciplines can accelerate the learning process to some extent. Familiarity with concepts like body mechanics, footwork, and timing can provide a foundation that can be built upon when training specifically with the katana.
5. Depth of study: The mastery of the katana involves not only technical proficiency but also a deep understanding of the underlying principles, philosophy, and historical context. Delving into the cultural and historical aspects of swordsmanship can enhance one's overall understanding and skill.

Given the complexity and depth of mastering the katana, it is difficult to provide a specific timeframe. Some practitioners may spend several years or even decades dedicated to training before attaining a high level of proficiency. However, it's important to remember that the journey itself is valuable, and progress and growth can be experienced at every stage of learning.