They could all be translated to 'when' in English but:

AとB in this case indicates that A first happens, then immediately after B happens.

たら can have more uncertainty in it, i.e. it can be used to express sentences where you'd use 'if' in English.

I think of とき as 'the time when' or 'everytime when'.

Just offering my two cents here. I am still learning too!:) But rather than the lengthy grammatical replies you usually get on this site, at this level I find shorter answers more helpful. Hope you agree:)

They could all be translated to 'when' in English but:

AとB in this case indicates that A first happens, then immediately after B happens. This is the case in your example!

たら can have more uncertainty in it, i.e. it can be used to express sentences where you'd use 'if' in English.

I think of とき as 'the time when' or 'everytime when'.

Just offering my two cents here. I am still learning too!:) I'm not good enough to provide the lengthy grammatical replies you usually get on this site, so sorry if it's a bit short. Anyway, at this level I find shorter answers more helpful. Hope you agree:)