What age is best?

Hi, I’m a 21 year old male with light skin and dark hair spread over my shoulders and at the lower arch of my back. I’m finding it quite embarrassing and distressing and so am looking into ways of having it removed permanently.
My question is that if I have treatments now does anybody know if I can expect further body hair to develop on the rest of my back, upper arms etc within the next few years and if so is there any way that I can prevent it now before it becomes visible?
Thanks to everyone, it’s reassuring to know that people are willing to offer information on what I consider to be an extremely embarrassing condition.

Everybody is different. I would suggest you to wait another year or two before the treatment.
It also depends on the age you started growing your body hair.