When I started, I knocked on doors for a few evenings until I got enough for a day or two's work. I did the work during the next available day, and when this work was done I resumed door knocking until I got another customer, which I was available to to immediately, and so on. Within a couple of weeks, of doing this, I had approximately 80 customers, at which point I stopped canvassing, and let the work come to me, which it did by recommendation, by being seen working by neighbours, or even some who had initially said no.
This method worked for me, as a) The householder was face to face with their potential window cleaner immediately, so a first impression was made there and then, b) I didn't have to wait for answers, it was either no straight away, or yes if I fitted the bill, c) no financial outlay for leaflets or paying someone to represent your interests, and d) same as 'a', except the first impressions were mine of the householder.
Another idea I found helpful was taking my wife and (at the time) 2 young children with me on some occasions. This showed the householders that I was in the business for providing for my family, rather than for 'beer money' or whatever. It did help create a favourable impression and it positively helped to get me some of my first customers.
Whichever way works for you, I wish you well and hope you do well.

John.