I always got the best results by activating the yeast first outside the bottle for 5-10 minutes. You want luke warm water to start (not hot). This will get your mixture rockin quick. I was able to get 1-2 bps within about 15 minutes with about 1/2 tsp yeast, 1/2-1 c sugar, and about 1/8 - 1/4 tsp of sodium bicarb. Filled that up to about 3/4 with more lukewarm water, and BAM CO2.
I used smaller bottles, and more frequent mixture changes, wich worked out very well for my tank.
The larger the bottle, and the more air space inside the bottle, the longer it will take for the co2 to pressurize enough to expel into the tank. But a larger bottle is good because the mix will become acidic enough to kill the yeast much slower than a smaller bottle.