I would get the schools your grades ASAP and send your rank when you can.
This at least gives the school a chance to open and organize your file and will cut down on your wait time later.
Also, if you have impressive grades, they may not care too much about the rank. In the same vein, if your GPA is pretty similar to last semesters, they may just figure that it hasn't moved all that much.
I got my information out as early as I could with everything and it ended up helping me a great deal.