I bought my first homebrewing kit through the Sam Adams homebrew contest. It came with a 'How To Homebrew" DVD made by Sam Adams founder, Jim Koch. He took 2 frozen gallon jugs of water, cut the plastic off and put the ice in his fermenting bucket to cool the wort. I was only doing extract brewing with partial boils at the time. I did this for a few batches until the day I forgot to put the meat back in the freezer after making room for my water. Needless to say, SWMBO was not happy.
I'm guessing you're doing full boils so putting the water bottles directly into the wort sounds like it works pretty good. A lot faster than setting the pot in a snowbank or ice bath and waiting for ever.
(I've got an immersion chiller now so everything is good)