Why Should You Talk To Her: The start of period is a major event in your daughter's life. If you have a positive conversation about it, it will help her to look at herself with positivity.
When Should You Talk Her: On average, most girls start their periods when they're 12 or 13 years old. So its ideal to have had this conversation before she turns 12.
How Should You Talk To Her: You can watch this fun video from HowToTellYourChild with her and then have a conversation with her.
You can also give her a Period Starter Kit that contains all the advise and things she will need for her first period.