Hi honey,
Its sooooo easy. Really its only as stressful as you make it. I also have a 10 year old girl and a 12 year old boy;both have absolutely no signs of hormonal changes-nothing. I probably started my talks with them when they were about 8. My mum started her periods at 9 eventhough i didnt till 15 i wanted the kids in the know. Not only for themselves but also so they can help there friends cause i remember when i was 12 my girlfriend got hers when we were skinny dipping(long story-girls only slumber party)and she thoughts sh'e durt herself. Her mum had told her nothing. So i told her and i had pads already for MY TIMe, so i fixed her up and took her to her mum. I remember being really angry at her mum because Julie was sooo frightened.
I started by introducing them to why i was crabby, or why i was a little weepy or why my tummy hurt, or why i wanted chocolate... Whatever goes on for you... Then just say Mummy is getting her period again. Grrrr mummy hates getting her period and tell them why.. Then just say "So babe/honey/chicken, has anyone talked to you about periods?" Do you know what one is? Maybe your friends have said something? I try and make it as casual as possible. You and her driving somewhere in the car.. Putting towels away while shes in the bathroom. Offer to wash her back and make a coment on how beautiful her changing body is. Lots of different ways. Its such a special way to establish that bond where she knows she can depend and trust her mum. Good luck with it all. I second the idea of a special little bathroom bag with pads,wipes and maybe a knicker change and something to cheer her up at the time;incase you arent there. Maybe a "Guess how much i love you sign"and a open in emergencies envelope with a 10 dollar coles gift card so she can by herself something to cheer her up and make her day special.
Love and light
Pauline