My two oldest daughters who is 3 and the younger who is 1 both wear khimar, but without the jilbab which make it hijaab. The older started wearing the khimar last winter, I felt I would start her them cause it would be cooler than summer and easier for her to adjust to, Insha'Allah.
She never had a problem with wearing it cause this is always how she saw me and her nana [grandma] when we leave our home. So when I first started her with the khimar I would remind her that she had to put it on, just to see if she wanted to wear it. So when spring came I wasn't going to put it on her anymore, but she through a fit jumping and crying, she didn't want to leave the house without her khimar.
So she never leaves the house without khimar now, Masha'Allah. Now as for the younger I'm just starting out with her. My mom [nana] put it on her when they came to visit me and Asmaa [my newborn] in the hospital, she looked so cute Masha'Allah. So now she's at the point where she has to have khimar on when she goes out as well, but when we get to our destination she takes it off with her coat , lol.
I try my best to encourage my daughters about hijaab in general , how wonderful and pretty they look in it, and that this is how we should dress. Yes, I know they don't completely understand yet but it's a start, Insha'Allah. Living in a society where anything goes [I'm American living in America], and is taken as "free" and we're viewed as "oppressed" I want them to feel good about hijaab and how they look. And I think I'm going to use Saajidah's technique saying "I'm a Muslim princess," Insha'Allah I will teach this to my daughters.
And Asmaa will also start wearing khimar around 2, Insha'Allah. Starting them out while their young is the best no matter where you live either it be America or a Muslim country. Don't wait till puberty by then it's to late, when young is best your instilling in them the values of Islam, Insha'Allah. And this also goes with our sons too!!!