Ok, I started my AT&T data plan on April 11th, to test it out, make sure it actually worked. I now know it works and all, so I want to cancel it, at least until I need it again in the future. The data plan says this cycle ends 05-11. Question is, when exactly should I cancel the plan, before the automatic roll to the next month happens? The day before, which would be today, or can I still cancel it tomorrow, on the 11th?