A lightbulb doesn’t always turn on immediately. The electron travel time is irrelevant in an incandescent bulb. Once the electrons have started flowing, the filament must heat up. This is incredibly slow.
YouTube is full of slow-motion videos of lightbulbs turning on. It can be recorded by any high-speed, inexpensive camera.
It feels instant, but the human brain is a lot slower than the lightbulb.
Your brain speed is something you don’t know. Literally, your conscious awareness uses some cognitive tricks to make it appear like you are actually interacting with the world in real-time.
Your eyes are also slow. Your entire nervous system is slow, in fact.
In my early days of neurobiology, I recall reading that a huge human being a mile high would be pinched on his toes by a crab while a rocket was being launched from his feet. The rocket would reach his head and the pain impulse would barely reach his ankle.
Your conscious awareness would still be around last week if the human nervous system was any slower.