User blog comment:The Sam Puckett/iCarly Wiki Bdays/@comment-4509465-20110812161341/@comment-3541132-20110814044957

As soon as you said that, I started singing the "30 days has September, April, June, and November. All the rest have 31 and that leaves February alone. And that has 28 days clear and 29 on each leap year.)

So, it's on the 31st.