I had nothing at all after six days, no "fizz" when I cracked the bottle open, no head (been married for a while, so I'm used to that). Not letting myself be concerned now, I'll crack anough next weekend when it's time to brew again; if nothing THEN, well, I'll be a little concerned....
My first time bottling, so it's possible the one I opened had too much or too little airspace (more likely the former). Takes a little bit of practice!
Oh, and it was corn sugar, not DME, that I used (part of the reason I was concerned with having zero carbonation).
Hell, I may crack another tonight - PURELY for purposes of SCIENTIFIC INQUIRY.