I would give the more time than the standard 3 weeks. 3 weeks is pretty much the minimal amount of time that it takes for the yeast to repeat the fermentation cycle, co2 to produced, and then become forced into the beer. Beers that are darker and stronger take even more time. I have a baltic porter thats been bottled for 7 weeks and is still not fully carb'ed. In addition, you want the yeast to form a nice tight sediment layer on the bottom of the glass so when the judges pour the beer (multiple times) they are not going to kick up a ton of yeast. Also make sure you clean your bottles better than you ever have before (I would use new bottles), and fill them correctly. I have entered 2 competitions (1 award!) and they will dock you for points if the bottle is filled to high or to low. Silly but true. Good luck!