Hi HampshireWindowCleaning
I am in same situation. I am going flat rate you get a 1% reduction for the first year too!
I am really going to put the pressure on advertising, van sign written, A board outside house, (we mainly do very large houses so not too much hassle), free advert on yell, door to door canvassing, email to all clients introducing refer a friend.
I have never advertised before as I had another company selling Christmas and got 90% of my clients from that and the rest from word of mouth.
I think once the ball is rolling you will be fine but maybe get an extra pair of hands part timer turning into full timer to help with all the first cleans. Let me know how you get on, maybe we can help each other out with pitfalls etc etc!