Hi Nicole!
I have never heard of that, myself. I took the film off with no problems, or at least my GC did. No vinegar involved.
I wonder, though, if the idea is to help the adhesive come off completely? In that case, perhaps you don't need to do it before peeling off the film, but you could do so afterwards.
There are certainly others here who know far more than I, so hopefully someone will chime in very soon! I'm glad to hear things are coming along for you so well. Removing protective film is an exciting step, isn't it?