When I posted to David, I was hoping for clarification, because I wasn't confident in my view.
At this point, I happen to agree with ros…that is, I too would bet that even life-long English speakers would interchange those words without even noticing.
If it helps, were it me, I'd use either "where," or "when" without compunction.
It helps immensely, Joe.
Believe it or not you have the ability to figure out any of these language issues if you are willing to expend the effort.
How could this be, you say, when you've not had any formal training?
Formal training isn't what is needed, especially the formal training in English that has been given over the last few centuries.
You have the ability because you know every rule that exists in the English language. If you didn't, you wouldn't be able to function in everyday life.
The expended effort comes from having to think about it and that definitely does take some effort.
Unlike you and Ros, David and Contrex rattled off some inane idea without thinking it through, an idea that stopped their thinking processes cold.