Yes, you may get your medical exam done before ITA. Call the doctors available in your country to schedule an appointment and tell them you would like to do an upfront medical exam. Most doctors allow it, but not all. Try the next doctor on the list if the first one doesn't.
See instructions from the CIC here:
http://www.cic.gc.ca/english/information/medical/medexams-perm.asp
Get your exam before you submit your application
This is called an upfront medical exam. To get an upfront medical exam, contact a
panel physician directly.
Once your medical exam is done, the doctor will give you a document confirming that you got a medical exam. Include a copy of that document with your application.
If the doctor works with the
eMedical they will give you an upfront medical notification printout.
If the doctor works with a paper system they will give you a copy of the IMM 1017B Upfront Medical Report form.
Attach that form to your application before you submit it to the visa office. If you apply online, you must upload that form before you can submit your application.
