Sonoff ZBMINI Extreme Startup time

Hi All,


I have normal switch to the bathroom (not the rocker one) and would like to use ZBMINI Extreme to turn the light off in the bathroom if anyone leaves the house.
The way I want to use it is to connect it after the switch, so the Sonoff switch would only receive power if the light is turned on.

Does anyone have this switch and can tell me what’s the startup time. In different words, how quickly it would turn the lights on (having it set for ON as power on default). I don’t want to buy it if it takes more than half a second.

Thanks in advance.