AutoPay should take effect on your next billing cycle. Keep paying your bill normally until you see a message in My CenturyLink or on your bill indicating AutoPay is taking care of your payments automatically.
In My CenturyLink, you will see a message similar to: "You've signed up for AutoPay."
In the My CenturyLink app, your home screen will display whether or not you're enrolled in AutoPay.
On your bill, you will see: "Your account is on AutoPay" or "Thank you for using AutoPay."
If you don't see a message in My CenturyLink or on your bill, AutoPay isn't working yet and you need to keep paying your bill normally.