[Grammar] 【Only when you...】should always be used in "present tense"?

[simile]

The sentence is like this:
Only when you noticed the change of her mind could you understand why she went to the US.

After my colleague read the sentence, she said if we use "Only when you..." to start a sentence, it should be in present tense. It's because when we use you as the subject in this sentence, it means giving the counterpart a suggestion. Therefore, present tense makes sense, but past tense doesn't.

My question is:
Doesn't it make sense in English to use past tense in "Only when you..." because the subject is "you"?
What if the context refers to something happened in the past?
When I'm talking to the counterpart, I'm telling him that I knew that she changed her mind but at that time he didn't know it.
So I say:
Only when you noticed the change of her mind could you understand why she went to the US.
This is to inform my counterpart that "At that time, you could understand why she went to the US only when you noticed the change of her mind."
Is there any logic problem, especially the logic of the time and the meaning?
Thanks in advance!

 

[simile]

Re: 【Only when you...】should always be used in "present tense"?

I think I have found the answer.
Yes, the pattern "Only when you..." can be used in the "past" tense.
Because I have found some evidence in
THE CORPUS OF CONTEMPORARY
AMERICAN ENGLISH

 

[emsr2d2]

Re: 【Only when you...】should always be used in "present tense"?

Where did you find the sentence you posted? It's important to quote your source if it's not a sentence you wrote yourself.

 

[simile]

Re: 【Only when you...】should always be used in "present tense"?

Do you mean the sentence in my very first post?
"Only when you noticed the change of her mind could you understand why she went to the US."
This is a sentence I wrote for an exam.
My colleague argued that it should be "always" used only in the present tense, so my sentence is not appropriate.
However, the context is important. If the whole thing happened in the past, why should I use the present tense?
Therefore, I found some evidence in the corpus. That explains already.