Agree with Dave Morris. It's a big riddle every day with matching work to staff, weather problems, vehicle problems, equipment repair and replacement, it goes on and on. Stick at it and you will win out, but it takes longer than most think. If you are not prepared for the long haul keep it simple, one man one van and under VAT. Window cleaning is great if you like cleaning windows, being independent , feeling free and outdoors. To take it to the next levels is tons of stress and beware of lack of cash flow that can kill you.
The systems builders will tell you it's easy - just like those that show those figures for network marketing and the like. Looks good on paper, but put vehicles and human beings in the formulas and it will take far more time and effort to achieve your goals.
Chris