Hard to say what the best advice would be.
I was in your shoes when I interviewed (i.e., I received interview invites in cities where I had applied to other programs but had not heard from those other programs). Because I had a lot of non-interview travel planned, I needed to at least try to string together some interview dates. So I just went ahead and e-mailed/called program coordinators at the other programs where I had not received an interview invitation as of that time. Some of the program coordinators were able to work something out with me, others were not. None expressed irritation that I would be so audacious as to call them before the official interview invitation had gone out.