we can use after, before, when and then to order events

1. Ordering events with before, after,
when, and then.
Action 1- I finished my homework.
Action 2- I watched TV.
I finished my homework before I watched TV.
I watched TV after I finished my homework.
I watched TV when I finished my homework.
I finished my homework. Then I watched TV.

2. I called a friend before I went out.
Before I went out, I called a friend.
When before, after and when come first, they
need a comma (,) at the end.

3. I left work. Then I met a friend.
I left work and then I met a friend.