The future perfect tense is not commonly used in English. It indicates that an action will be completed in the future (usually before some other action or event).
I will finish my Russian course in June. In July, I will begin studying Chinese.
By the time I begin studying Chinese, I will have finished my Russian course.
When I finish this race, I will have run a total of five miles.
Before they leave for Miami, they will have visited Houston and New Orleans.
The important thing to remember is the time of completion
. (Beginning time may vary.)
I started studying last year. I will have passed my exams when I graduate next June.
I am studying right now. I will have passed my exams when I graduate next June.
I will start studying next month. I will have passed my exams when I graduate next June.