AT&T is not going to do anything for 10 days. They want month's commitment. I would just sign up for a month with your credit card and terminate right then and they will only charge for a month. I do it all the time when I am traveling and not sure if I will be able to find WiFi. Just watch your data usage as depending on what you areamdong you can use it fast.
You can sign up for the 30 day 3GB plan ($30) or 30 day 250MB ($15). Just make sure you cancel the plan because otherwise it gets automatically renewed at 30 days. You can cancel from your ipad before the month is up and you have the option of canceling on the spot or when the 30 days are completed.