Rule of thumb ... just don't wear it until someone comes up to you and says "hey there killer, where is your GWOT medal? You know you rate it?"
In theory, every award/ribbon you rate should have some kind of backing paperwork in your record, even if it's just a Pg 13 entry. I found that the admin folks were real good at doing that while I was enlisted, but as an O, you really have to keep on top of it.
Brett