This is a great time to introduce it. I started around 6 months, and it took dd a good month before she'd sip from it. It's such a different feel in their mouth, and it's different to get what's in it out. I use water, watered down juice, and I've tried putting her formula in it. However, she won't take the formula in it, I suppose because she doesn't understand because that's "supposed" to come from her bottle. She doesn't drink much water, just a few sips with lunch and dinner, and if it's hot out and we've been playing.