When should I use the Future Continuous?
(Also called the Future Progressive)1: We use the future continuous to talk about an action in the future that overlaps another, shorter action or a time. The action in the future continuous usually starts before and might continue after the second action or time. This is very similar to how we use the past continuous in the past. The verb after 'when' is usually in the present simple.
- I'll be waiting when you arrive.
- At eight o'clock, I'll be eating dinner.
- The Government will be making a statement later.
- When will you be leaving? (This is more polite than 'when will you leave?' because it's definitely not a request for you to leave.)
Try some exercises about the future continuous here.
If you want to learn more about the tenses, especially about how to use them when you're speaking, you could try Perfect English Grammar Plus.