This is a hard one. I think the English answer is not something someone would say explicitly (using "THAT visit") unless there are other visits to compare it to.
A normal person would say "When did THE visit happen," or, "When did THE visit take place."
But if THAT were the case, the Indonesian sentence should have been: "Kapan kunjungan YANG ITU terjadi?" --> "When did THAT visit take place?"
If "THAT visit" were to be emphasized, the Indonesian "itu" should also be emphasized to "yang itu". Otherwise it's ambiguous and "the visit" should be acceptable as well as an answer.
Editor, please revise.
They are interchangeable. A bit difference is "that" emphasize more on the object or context.
For example: Why did you suddenly wake up last night?
Because i heard the strange sound(s) - Karena saya mendengar suara(-suara) aneh itu. "The" here is a definite article can be one specific object or more than one.
Because i heard that strange sound - Karena saya mendengar suara aneh itu. "That" here is also a definite article. But the stress is on "one and only specific object of interest".