I don't think you can beat building up your own round, canvassing can be hard/frightning etc.. depending on how you view it, but YOU get to meet your future customers, they get to see you and you also see the property and any pitfalls/problem windows.
many times i have been asked if i am doing the cleaning or am i local, yes is my answer to both and i feel that if i was a canvasser i'd get a no.
It's all good experience for you dealing with custy's and getting the pricing right and what services you are going to offer them 4/8 week etc...
you will make the odd mistake but be better off for that experience
Darran