To paraphrase the Right Honourable Revvy, opening a beer early "just to test it" means one fewer beers when they're nice and properly carbonated.
I can't fully explain it, but something magical seems to happen to all my beers at two weeks and two days. A two-week bottle-conditioned beer is still a little flat. 16 days is good. Three weeks is usually better. I've never, ever regretted waiting a month.
That said, I waited all of five days to try a bottle of my first ever brew, and it didn't suck. It was flat, yes; and it was yeasty, cloudy, and tasted of cider, but dammit, it was beer I had made - therefore a beautiful thing.
What was the OG/FG of the beer? Big beers carbonate more slowly.