My eldest started school at 4, and this is quite normal in Scotland. It depends on the child of course, but most cope really well with it. My youngest two will start a few days after they turn 5, and whilst for my daughter this is no problem (she could easily attend now aged 4), my son will have more of an issue. I wouldn't send him if he wasn't a twin. It's such an individual thing but you know her best and if you think she is ready, she probably is.