17 weeks pregnant, too soon to show?

I'm 17 weeks pregnant, this is my first child, and I was pretty thin before I got pregnant, & a lot of muscle. My "belly" kind of comes & goes, some days its all out there & proud, other days you can barely see it. A lot of people are saying I don't even look pregnant. But here for the past couple days its been steadily poking out. Is it too early for me to be showing? Or am I right on schedule? I know everyone is different, I'm just wondering... Thanks!