Cuando is always used with past tenses in the indicative to express "when something happened/has happened/had happened". We understand that these actions actually took place, there is no doubt about it.
Cuando + subjunctive
If we use past tenses in the subjunctive with cuando, then we will not be referring to past events but future or hypothetical events.
Here are some examples:
None of the above refer to actions that actually happened in the past.