I can't figure out whether the last word should be "works" or "worked."

In September, John's son started to go to day care while he works/worked.

I think "works" sounds better. "Worked" seems to indicate that John worked in September, but doesn't work any more. With "works," it sounds like John is still working now and that his son is still going to day care.

But isn't there a rule that says it has to be "worked"?
No, the rule is the past, the present is the exception here.
Teachers: We supply a list of EFL job vacancies
So would the correct word be "worked," not "works"?
See, the problem is that I think "work" COULD be correct in some instances. Here's another example:

Option 1. We decided to teach our son to drive while he was on vacation.

There's little doubt that the above sentence is correct: We decided to teach him to drive during his vacation, which is now over. But what if I were to say:

Option 2. We decided to teach our son to drive while he is on vacation.

I think the second sentence could also be correct IF the meaning is something like, "Our son will be on vacation next month. We decided that we're going to teach him to drive during that time."

Anyone think option 2 is wrong? If so, why?