I started to think I felt the baby moving around 17 weeks. But I wasn't sure it was the baby until about 20 weeks. One of my favourite pregnancy books "Your Pregnancy Week by Week" by Curtis and Schuler says the following may happen as early as 16 weeks:

"Many women describe feelings of movement as a 'gas bubble' or 'fluttering.' Often it's something you have noticed for a few days or more, but you didn't realize what you were feeling. Then you realize you're feeling the baby moving inside you!"

"What to expect when you're expecting" says that mothers feeling the first movement can happen anywhere from weeks 14 to 26 with the average being somewhere between the 18th and 22nd weeks.

It was a few weeks after I felt the first movements before my husband was able to feel the baby too. The kicks are so gentle at first that only mom can feel them. I think he started to feel the baby kicking around 26 weeks. But I'm sure this will vary from women to women.

I remember going for my 18 week ultrasound and still had never felt any "fluttering" yet, like the books had said I might have. Exactly a week later I was sitting around and felt a funny sensation- a quick couple of taps in the area where I have only ever felt menstrual cramps before in my life- it was such a cool feeling when I realized what it was! Within days they got a bit more intense and when I was lying in bed, if my husband pressed his hand on the under part of my uterus, he could feel them, too- he said it felt like someone "flicked" him (with their finger) through my skin. So, in my personal experience, we both felt it at about 19 weeks.