Huggles,
Wha ha ha about the shwising discovery!!
I think that even just swishing will help. I have read that often disease starts in your mouth especially the tongue as germs breed here. I think it moves to your throat from there and then the rest of your body...
My sister started teaching her 2 kids at age 3 (I though that was really early...but I guess it depends from child to child). She also swears by the saltwater method and has stopped numerous colds in its tracks!
I still don't know how she got it right. I showed her how I do it and tried to explain she must practice not to swallow the water. Encourage to take only small sips of water in the beginning when she starts. I think what motivated her was that I gargled tunes to show her how fun it can be. She thought that this was brilliant, so she kept on trying until one day while in bath she called me and she just figured it out! When she got it right with just plain water we moved to salt water (1/4 teaspoon salt to 1/2 cup water). Now everyday it is a game of her gargling a children's song and we must guess what song it is! She is gargling like a champion! She does it twice daily, morning and evening along with saltwater nose spray. Her colds has reduced 50 - 70% in frequency since we started this routine.