You always want to practice your test elements on the ice surface where you'll be testing. If you can do it sometime in the week leading up to the test, that's great. If you have no choice but to do it the day of the test, I think it's still better than not doing it (but, of course, don't tire yourself out). Different rinks have slightly different dimensions, and some rinks have slower/faster ice, or even hills on the ice that you need to compensate for. And all rinks have different visual cues, which can play a bigger part than you realize.