I changed my site's time zone after setting the times

The Switch on at and Switch off at times are kept as you typed them and read in the time zone your site has now, under Settings → General. So after a change they mean that time in the new zone, and the scheduled switch-on and switch-off move with them. A time the new zone has already put behind you takes effect straight away: visitors see the site, and the scheduled switch-off runs and emails your list as it would have. If a time reads wrong on the Dashboard, set it again under Settings → Schedule.

If you changed the time zone before updating to this version, the switch-off may have run early and been lost: the Dashboard said the switch-off time had passed while the mode stayed on. Updating runs it. Within a week of the switch-off time it emails your list as it would have; later than that it emails nobody, and the Dashboard offers Send the launch email, which asks first.