Hey there, @Angel11-72. You're in the right place.
You would want to use the issue date or invoice date on your bill, as this is the date that the Vendor (Utility Company) issued you a notice of your balance. You can also enter the due date as shown on their bill.
For more information on entering and paying bills in QuickBooks Online, I recommend: Enter and pay bills
Let me know if you have any additional questions. I'll be here to help.