I am also prone to canker sores...my entire mouth full it seems like sometimes. My mother got them, my daughter gets them.
So far I have not gotten any and I'm on day 5. However, I started taking olive leaf extract (quadruple the dosage) several weeks ago and have not had any since then. During my Master-Cleanse I can't take it, though, so I was afraid that they would return. So far so good.