sorry to say, but yup I would've started earlier! BUT it's not too late to instill good practice.
We started our lo's right at birth. I would rub a cloth on their gums. We bought DS his first "toothbrush" at 8 months. You have to be really careful that they don't put it down their throat.
Does she watch you brush? That's what we did to make our DS laugh. I would let DH brush mine for a bit and then DH would ask DS if he could try and we'd let him brush ours.
He is FABULOUS now at brushing his teeth (in fact some nights it's a fight to get him to put it away!) Most nights he lets Mama "check" and I do a quick once over. Some nights he adamantly refuses to open his mouth for me. If DH is home I ask if Daddy can do it. But nights where he says NO WAY...I just say okay mommy will check in the morning!
Big thing is, don't push. Make brushing a really positive experience. We went through a phase where he wanted a brush like ours. Now he wants the "cool" ones.
Just remember to use a soft bristle brush and a child friendly toothpaste. Good luck and let us know how it goes!