The Future Perfect expresses the idea that something will occur before another action in the future. It can also show that something will happen before a specific time in the future.
By next November, I will have received my promotion.
By the time he gets home, she is going to have cleaned the entire house.
I am not going to have finished this test by 3 o'clock.
Will she have learned enough Chinese to communicate before she moves to Beijing?
Sam is probably going to have completed the proposal by the time he leaves this afternoon.
By the time I finish this course, I will have taken ten tests.
How many countries are you going to have visited by the time you turn 50?
Notice in the examples above that the reference points are in Simple Present rather than Simple Future. This is because the interruptions are in time clauses, and you cannot use future tenses in time clauses.