If it suits your needs, I would recommend to use the Netatmo integration as your netatmo system will itself always be a backup system.
Otherwise, you would need to add the zigbee devices to HA, and setup a scheduler method in HA. You may go further and control the valve’s opening % from within HA (if the individual thermostats permit it) and use a temperature regulation from within HA.
Unfortunately, I do not know of a solution yet where (using HA), I can define the time at which I want a certain temperature so that the individual valves would start heating the required time before. I currently have a central thermostat that works like that: heating starts at a variable time before the target time according to the actual temperature and the estimated “heating speed”.