Most girls in India get some information about periods from friends or the internet before they hear it from a parent. Getting ahead of that — even briefly — makes a real difference in how a girl feels about her body when the day comes.
You don't need a single 'big talk'. Short, matter-of-fact conversations from around age 9-10 about what a period is and why it happens work better than one long, awkward one.
Keep supplies (pads, a spare pair of underwear) accessible at home and in her school bag well before her first period, so the practical side never becomes a source of panic.
Through our Shevolve initiative, we run school workshops covering exactly this — menstrual health, hygiene and hormonal changes — in a comfortable, judgment-free setting for young girls.