Despite how useful the candy frog may look, it takes much too long to charge it up and keep the bombs in check at the same time. Focus on removing bombs and creating special candies. It is possible that through cascades, the frog will charge up on its own, but try to only use it if there is a group of bombs you may be unable to destroy. However, using a colour bomb to clear candies matching the colour of the candy frog will not only instantly fill up the candy frog, it can clear some candy bombs in the process.
If you focus on creating special candies, especially a colour bomb or two, you should have no problem completing the order.