buying a round is probably the best way to go, from my point of view.
i bought a small round and had work canvassed, i still have 90% of the round and have almost nothing of the canvassed work.
the round customers are used to having a clean and don't really notice if the person doing it changes, and you can earn from day one.
new customers can take a free clean from you and never pay, mess you about, then cancel. others start well and the forget to pay so you chase them for weeks.
(the canvassing wasn't where i wanted it though)