What age is good for an iphone 5?

I hope I'm getting an iPhone 5 for Christmas but only if I get good grades my dads girlfriend has a contract for them and my oldest sister says I'm not getting one, what's the best age I'm on my sisters account but I'm 11 and my other sis already has one

I have 5 sisters

Young children drop stuff very fast so i'll say just get a cheaper one and upgrade from time to time