〜まで

A まで means "till A." The A in "A まで B" is the description of the change that coincides or causes the end of B. The A, therefore, is usually a verb of the "change" kind. The verb in A is always in the present tense and in the affirmative.

にほんごがじょうずになるまで、くににかえりません。

I will no go back to my country, till I become fluent in Japanese.

When the subject of A is different from the subject of B, the former is marked with the particle が rather than は.

あかちゃんがねるまで、わたしはうたをうたってあげます。

I will sing a lullaby till the baby falls asleep.

You can use "A まで B" in the sentence describing a situation in the past. Note that the verb in A is in the present tense nonetheless.

にほんのせいかつになれるまで、たいへんでした。

It was tough untill I got used to Japan.