This depends on the type of medical, the tests that need to be done, the pilot's age and medical issues. In general, you should allow:
• Class 1 - 45 to 60 mins
• Class 2 - 30 to 45 mins
• Class 3 - 45 to 60 mins
• Optometry - 60 to 90 mins (Initial Class 1 & 3 only)