Ok if you are a confident person with very good hand eye foot co-ordination you may be up to standard within 20-25 lessons with some private practice.
If nervous of new things and lack a little self confinedence but have co-ordination you may be up to standard within 30-40 lessons with some private practice.
If you are very nervous with little co-ordination well you will probably need 40 + hours with plenty of private practive, these observations are from years of teaching.