this is something we have never done, but i know alot do and im thinking of adding it in next year.
I would like to know how others do this? how much extra do you charge? and do customers ever object or question the reasons why?
Depends really Lee. If it's a job I really want and I sense that charging more on a first clean might put them off, then I don't do it.
If I do do it, I charge an extra 50% and go round it twice - The first time I scrub all the glass and framework (including tops).. The second time, I just brush and rinse the glass as the dirt from the top of frame has usually had time to finish trickling down by then. If doing it this way, a bit of time can be saved by doing the first pass on each side of the house on both (all?) levels - i.e. it doesn't matter whether water is still running onto the window below. Obviously the second pass needs to be done in a sequence that ensures water from top has stopped - or slowed enough to work on window below it. It just saves on hose moving.
I do make it clear to the customer that there are sometimes "imperfections" on the first clean and going around it twice helps to keep them to a minimum. They usually feel more OK about paying it then as I explain to them about the trickling from frame tops. If money is a bit tight for them, I just tell them that there is a possibility of the first clean being imperfect that that will get better over the first couple of cleans - but I only go around once.
The way I present it is that it generally takes me a lot longer to do the first clean but I'm "only" charging 50% more. I call this "sharing the extra cost of the first clean with the customer" or similar to that. That way, it can feel like I'm actually giving them something. In fact, on very dirty first cleans, I sometimes AM giving them something as it can take ages - as you know.
Sometimes I choose to go around twice and effectively work for less on the first clean - but only if I get a strong feeling that the customer will be a good regular.