At press time we are 19 days away from the new routing, which simply must bring about a schedule change, since the route is supposed to be 40 minutes to an hour shorter, and "new" stations are being served while Amherst is being eliminated.
So far, nothing in the way of a new timetable, and the times loaded in the inventory are the same for sample stations along the Vermonter route north and south of the reroute. My guess is that Amtrak will leave the schedules for 54, 55, 56, & 57 alone on the southern end to preserve the Vermonter's timeslot on the Northeast Corridor and along the New Haven-Springfield route, while serving Vermont stations earlier northbound and later southbound.
If anyone wants to ride the new trackage, it will be impossible to do in one day, unless you live along the Vermonter route in Vermont or New Hampshire. The two Vermonters, if on time, pass just south of Springfield, MA. So it would require an overnight in White River Junction, Bellows Falls, St. Albans, or the Essex Junction/Burlington area.