Various feature on the face contribute points to either a male of female gender call. More male points, your a male. More female points, your a female. The brain does this automatically but not always the same. In the 1960's when male long hair became common, a young male, clean shaved with long hair would often be called a girl. Today, long hair doesn't have as much impact on the balance and people look for other markers.
The most important reason for starting early on electrolysis is because you need about 3 day's growth for treatment. Trying to present feminine with 3 day's growth is rather difficult so it's best to get to the point where you don't need to do it often or the hair no longer shows after 3 days.
In addition, some people get dysphoric over shaving and it's just so nice getting ready in the morning without needing to shave. It's also nice to rub your hand across your face and not feel any bristle.
I think laser takes something like a year to get the facial hair under control. Electrolysis takes somewhere around 200 hours give or take. With electrolysis some people can take 4 hours a week. I did it with 2 hours a week and by a year and a half I no longer needed to shave and was constantly growing the hair out for the next session.
