The choice depends on whether the time is finished or the action still connects to now.

Form	Use	Example
simple past	a specific, finished time	I saw him yesterday.
present perfect	no specific time, or a connection to now	I have seen him before.

✗ ~~I have seen him yesterday.~~ ✓ I saw him yesterday.

Connection to now	Example
life experience	She has run two marathons.
change up to now	The town has grown since the new line opened.
unfinished period	I have had three coffees today.
first time	It is the first time I have seen snow.

Questions with when ask about a specific time, so they take the simple past: When did you arrive?

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