How long before you got a positive pregnancy test?

I'm just wondering how long it took some of you other ladies to get a positive test. I am a week late, and I'm still getting a negative. I know that doesn't sound like a very long time, but I am NEVER late, and I see a lot of other women saying that they had a BFP on the first day of their missed period or before. I am beginning to get worried, and I'm just hoping that maybe this is more common than I thought.