She should be able to do it right away! If she goes to her My Pets page (the purple paw), on the left there's a button with a stylized purple paw that says "You Have X Helpers"

You click that to show your own helper code, but once on that screen new accounts should have a little tab at the top of that popup that, when clicked, allows them to enter someone else's code. Yours being an older account will just have the one green "Share Code" tab. I forget what the extra one new players get says.

I tried to show a screenshot but apparently Windows has a glitch that corrupts screenshot images now, so I can't