You only get bubbles once you open the bottle and relive the pressure and the dissolved CO2 precipitates out of solution. While the cap is on and pressure maintained then the CO2 is sat in solution in the beer.
One of life's lottery moments... The second before you pop the cap has your bottled beer carbonated???
You could cheat and use PET bottles and give the bottles a squeeze. If you have successful carbonation the bottle will be hard.