Tough one but it's another milestone for your little princess. I would suggest that since she is entering the puberty stage, it would be best to bring her to her female cousins or titas whom she can get advice in dealing with her first monthly period. If only because it will be awkward for her (and maybe you, too) to discuss preparation and even choosing what napkins to buy, etc. But it is a good thing to know that you are there to support her every step of the way.
Jim Baluyut