You'll need a thermostat that can take that into account and begin heating at appropriately early times.

and what smart things you put in your rentals (other them smart locks, thermostat, outside cameras, and lights)? 

No one turns on the central heater at home so should I install a smart thermostat to keep the house at a consistent temperature?

I control the thermostat and got central AC added to help keep costs down since I include utilities. in the ward I suggest looking around the area where the university shuttle goes.

I put in all new smart thermostats (dual zoned HVAC system), new mesh wifi system, outdoor surveillance cameras and doorbell cam.

There’s only 1  thermostat in the downstairs unit.

Mine can set door codes, message (or call) guests, schedule cleaners, adjust the thermostat, monitor my cameras, & call a plumber just as easily as a local PM can, for 1% of the costI wrote much more about leveraging offshore assistants in this post here.

How is everyone handling when a tenant moves out and has their smart phone connected to the Nest thermostat?

Often times the issue is that the resident did not turn the thermostat to the appropriate setting: Heat/AC.  

I look the thermostat and it was set to 80 degrees...