What If There's an Accident?
Without any pressure, your child, even one who's been reluctant to try to go on the potty, will be able to subtly begin training. To them, running around naked is just a new way to play, but as soon as the first accident happens, they slip naturally into potty training.
That first accident can't really be considered an accident, because they haven't yet learned the correct behavior. Because you aren't letting them know this fun nude game is about potty training, the first time they pee or poop during nakedtime will serve as the introduction to the idea of going on the potty. When your son or daughter goes, you should point it out in a matter-of-fact tone and explain that happens with everyone. At this point, your child will be more likely to really listen to and absorb the overarching biological lesson you give him/her. Typically, kids don't like having pee or poop all over themselves, and so you can naturally and casually show them where the potty is and how they can use that the next time so it won't be so messy. This first "accident" is all about observation and the dawning of knowledge.
At first, when your son or daughter pees, you'll probably have to point it out—she or he may not even notice it is happening until they feel it start to trickle down their legs. Most likely, they will not be able to stop mid-stream. Recognize this and talk them through it.
Talking to Your Child:
Mom: Oh, look, honey, I think you're going pee-pee.
Child: (upset) Mommy!!
Mom: That's okay. Look, we can clean you up real quick. You know, if that happens again we can run super fast to the bathroom and you can go in there just like I do. (Or, if you're already in the bathroom: When this happens, you can just sit on the potty like Mommy does. Do you want to try that now?)
Many children will be distressed by the pee running down their legs at first, and you should react with the same calm, relaxed demeanor you have when talking about anything potty related. If your child hasn't yet tried to sit on the toilet, now is a good time to broach the subject, but do not unexpectedly put them on there while they are already dealing with the stress of their first accident. Offer the option of trying it right now; there is a chance your child tensed up enough to stop their stream and perhaps has a little more pee they can put into the potty—and hurrah, you have a fantastic experience upon which to kick off your potty training in earnest.
If, however, your child recoils from your suggestion to sit on the potty, respond in the same composed manner, "That's okay, maybe you'll want to next time."