You may be eligible to work in Canada while studying, if your Study Permit includes a condition that says you can work on or off campus. You must also meet all the other requirements. You can only start working in Canada when you start your study program. You can’t work before your studies begin.
Visit the Canadian Government Website for more details at http://www.cic.gc.ca/english/helpcentre/answer.asp?qnum=495&top=15