Houston is 17 hours behind Wellington
Best overlap: 8:00 AM to 11:00 AM in Wellington is 3:00 PM to 6:00 PM in Houston.
Target 8:00 AM to 11:00 AM in Wellington, which lands at 3:00 PM to 6:00 PM for the Houston side. Houston is 17 hours behind Wellington, so the practical overlap is about 3 hours — generous enough for meetings, tight enough to be worth booking ahead. The date rolls over between them: Houston is on the previous day relative to Wellington during these hours.