Japanese primary schools are expected to increase English classes gradually by 2020.
I'm confused about the combination of までに (by) with 少しずつ (little by little) . The direct English translation makes no sense. You can't do something 'little by little' by a certain time. I think the only way I could understand this is "they have until 2020 to start increasing the number of English lessons'.
You can do something 'little by little' until a certain time.
You could also say something like 'expected to increase classes little by little until they reach two hours a week by 2020'
So I think my question is why までに rather than just まで? What does this sentence actually mean?