If all humans were killed instantly and you were the only survivor, how long would electricity keep coming into homes If you was not actively generating it yourself?
Different types of plant would run on alone for different times. As they successively shut themselves down (normally due to loss of fuel supply) so the total power to the grid system would reduce and areas would gradually experience loss of power as they too were successively shut down. Coal fired plants would start dropping out after a few hours, depending on their local coal stocks and the degree of automation in feeding it to the crushers. Oil and gas fired plants would follow mostly within days or weeks. Some nuclear plants and hydraulic plants (water supply assumed) could conceivably continue to run for many months until a fault caused them to trip off.
I being the only survivor would not matter!