I would need the use of this device especially for the bedroom. We have rather dry air due to the room ventilation. To prevent it from running unnecessarily all day, a timer function would be great - but it doesn't seem to have that... My idea would be to solve the problem with a timer that switches on from, for example, 17-23 hrs. My question: Does the unit switch itself on as soon as it is connected to the power supply or do I always have to press the "Power" button first for it to run?