Never too early to start. Whenever she seems interested I would go for it. My daughter is 12 months and I've started to introduce the toilet to her. She sits on it but doesn't get the concept yet.

I would day follow your instincts and the signals from your little one. I don't think it's a such thing as "too early" after age one of you follow signals and your mommy intuition. Go for it, you don't have anything to lose in trying. Good luck momma