I'm 15 and I live with my mom and I want to tell her I want to be a nudist I don't know how though.

Fifteen!! Anyway... you seem to know what you would be saying to your mum and you know she will NOT LIKE HEARING THIS and I would not lie she will LOVE the idea. Therefore, the thrill to be nude seems to be quite there however, before suggesting this to your mum... How much research have you done on being a nudist? Have you tried this before and if not what are its pros and cons?
Are you ready for that kind of attention including psychopaths stalking you with strange messages?

The kind of attention you are looking for needs tonnes of caution than attention. Kindly make this a last option after all factors considered.

So at 15 when will you start being a nudist, what nudist camp will you be visiting soon?

If the answer is none, then no need to tell her what you plan to do in 3 years or so in the future, after you are grown and don't have to follow her rules