It is important to book your wedding ceremony officiant as soon as possible after you have booked the venue of your ceremony, especially if you plan to be married in the popular months, April to October.
Civil marriages in Ontario may be performed by a judge, justice of the peace, or municipal clerk, under the authority of a marriage licence.
Each municipality may offer civil marriages and may set its own fees. For Toronto, see the following link:
Registry Services, Marriage Lisence Requirements
HINT: Try to find an officiant who is close to your ceremony location as travel costs can be a consideration. Sometimes your contact person at the ceremony location can recommend a officiant who lives nearby and is familiar with the site. When you hire the officiant, make sure that the fee and payment arrangements are clear.
You may also wish to look at the following link for more information about getting married in Ontario.