Very good communication with the host, who is very kind and was flexible enough to change my booking on the day itself. I had booked the wrong month but had already arrived in Madrid. haha! She changed my booking so that I could indeed stay from the day that I arrived.
It's not a central location but very close to a metro station from where you can easily reach all parts of Madrid.
Good wifi and your own keys as well as one for your room.
P.S. Be careful to not hit your head against the turning knob of the bathroom heater ;>)