I assume you mean 9am?

The fastest way would be by cab.

If you have bit of time to spare, you can save some money by taking the shuttle bus http://www.torontoairportexpress.com

Cheapest method would be by bus/subway, but you would have to budget a little more than an hour http://www3.ttc.ca/Riding_the_TTC/Airport_service.jsp



But I would second the recommendation to come in the night before and stay at a hotel. This one would be the most central in downtown, though there are others - http://www.onekingwest.com