I started at about 40. I have only ever had the kind of electrolysis where the beautician sticks a fine needle into the hair follicle and gives just a short sharp burst of heat to kill it.
It can take a couple of applications to kill the coarsest hairs, and of course, as fast as you get rid of one set of hairs, others grow. However, I have always had a lovely thick head of head of hair, unfortunately, that applies to anywhere else hair grows and without electrolysis I would have a beard to rival my husband's or a visibly shaved face.
I am sure there will be others whose experience is not as happy as mine, but from my point of view, it is marvellous. The one downside, it can be painful and I have never got past 10 minute sessions. That is sufficient.