Sorry, Never done one before that is why I am so many questions.  A customer of mine said I can practice on his so thats how I will start.  Will get the 3.3M one first and just try with fairy.  Should give me an idea on time so how much I should charge.  Suppose I will not know until I try.
I expect it is just like cleaning the windows in that you get a better judge of pricing with experience.  I know I made some right gaffs when I first started.