New IBR vs Old IBR question

I am planning out what I need to do with SAVE fiasco. I'm trying to figure out if I would qualify for New IBR or Old IBR before I officially submit an application to switch. I had undergraduate loans that were completely paid off November 2014. I went to graduate school starting May 2015 (first graduate school loan starting then). I believe you are automatically put on Old IBR if you have loans pre-2014, but does the situation change at all if they were completely paid off? Would I be considered a "new borrower" for my graduate school loans? I asked Federal Student Aid and they were adamant that I would qualify for New IBR, but it's my understanding they don't make that decision, MOHELA would. Any help would be greatly appreciated!