When do you consider starting short-term DAPT in patients who present more than 24 hours after the onset of a high-risk TIA or minor stroke syndrome?  

Immediately. Unless tPA has been given, then at 24 hours.

The literature states that DAPT is most effective when started within the first 24 hours after such an event, but is still effective as far as 72 hours later. So if the patient presents more than 24 hours later, but not later than 72 hours, I would still start it then but would want a CT scan first.

Typically up to a week from symptom onset, not based on data.

Immediately if no absolute contraindications. If treated with TNK, in 24 hours after confirmation of no hemoconversion.