When i made my first batch of yeast generator, it took almost a whole day to really get going. Now when i make it, 2 hours tops, and it's full blast. There are a few variables though. I always use hot/warm water to activate my yeast. Also, i use the same temp water to mix up the sugar/baking soda in the bottle. After all ingredients are added, i try to keep the bottle in a warm place until ready to be hooked up.
Did you activate your yeast beforehand? Did you mix up your other ingredients using warm water?