I'm having a migraine headache, I took excedrine migraine about 7 hours ago, can I take an Advil (ibuprofen) or excedrine extra strength now?

No. You should not not take more than 2 tabs in 24 hours, unless directed by a physician. I can not suggest taking any more of this drug or any other drug of this nature until 24 hours has passed. If however you are feeling extreme pain please go to a clinic for an exam.
YES. Try not to use 2 diffent medicines: You may want to try Aleve, (naproxen) 1 tablet every 8 hrs. or Advil- 2 tab. every 6-8 hrs ( not both ). DO NOT MIX EXCEDRIN MIGRAINE WITH NSAIDS- USE ONE OR THE OTHER. 7 hours is sufficient time to change medicines.