Agreed with FKL....
It is not mandatory that you need to land at the location where you will work (if it is a port of entry), if you have already worked in canada and are coming back again, then the immigration officer might not ask you anything, but, if you are coming here for the first time, then, it might raise some suspicion. You will have to have a strong reason to justify why you landed in Toronto.
Things like Cheaper air fare, lesser number of connecting flights, vacation time, your hotel / accommodation booking confirmation at Vancouver will help convince the officer.
P.S - I landed in a different city though the original work location is closer to a different port of entry, however, since I have worked here before, the officer didnt ask me anything, moreover, the officer was so kind not to lock me with the city that is mentioned in LMO but the officer gave a TWP that allows me to work anywhere in Canada but with the same employer. ;D