Dave mate chill...a bloke round here needed to hit the ground running the same time as I was just building my rounds.
He employed a canvasser and canvassed nearly all my work in a small town near me. I Lost a few as they were nearly 40% cheaper. After a period of time I had a few phone calls asking me back as this chap had disappeared, I took back 3 out of the 5 I lost at a higher price knowing I might get dumped again. That was two years ago and still have them, canvassed work is unreliable IMO as you are asking and they are not asking. The bloke who started up disappeared as quick as he appeared.
I prefer to advertise and word of mouth is almost bulletproof work.
I worried all the time and still do to a extent but after talking to long established shiners they tend to put your mined at rest.