Speed of progress for beginners

Absolute beginners, roughly speaking, need 60 hoursfprivate tuition to cover the grammatical functions required for survival and another 60 hoursfto complete another set of essential grammar to be able to cope with numerous situations in Japan such as conversations with shop-assistants and hotel staff, asking directions in the street, ordering in a restaurant, expressing feelings, reporting what someone said in direct/indirect speech.
Any extra work done at home will help accelerate the learning process.

Homework

To make the most of these lessons, students are expected to do as many hoursf homework as their weekly tuition. If a student has two hours of private tuition, they should do two hoursfhomework.

Class work

Minnano Nihongo Volume 1 and 2; each contains 25 chapters. Ideally, I would like to cover one chapter per lesson, which ranges from one to two hours. A simple calculation tells you that you need 25 lessons to complete volume 1 and another 25 lessons to finish volume 2.
So in total, one probably needs at least 50 hours' tuition. I can squeeze one chapter into one hour but extra activities, such as listening to a tape, would have to be excluded.
But if you are prepared to work hard on your own at home, thatfs fine.
However, if you can afford it I could recommend that you take 1.5 to 2-hours' tuition so that you will be exposed to various types of activities, such as listening to a tape, or extra oral practice, etc all of which help enhance your awareness of the Japanese culture and language, as well as your weaknesses.