I bought my 3G iPad Wednesday. I decided to wait until yesterday (the 1st of the month) to enable 3G with AT&T. I filled out the screens, put in my CC data and within a couple of minutes, 3G was active and has been working since. However, AT&T has yet to bill me. There is not even a temporary hold showing up. Anyone have experience on how long after initial sign up and how long before the new month begins before AT&T bills for the service?