ANDY'S ANSWER: Well, you could keep it to yourself, but why would you? It's an exciting time and every one of the girls in your class is also waiting for their period to arrive. Someone has to be first, and if it's you, it's you.

If you don't say something until the next girl gets hers and then you say, "Yeah, I've had mine for a long time already, I've just been keeping quiet" ... it's just going to look like you're trying to steal their thunder.