I am in 2 minds over this. I can see both sides of the story but am inclined personally to agree not to do 1st clean free. Firstly as already pointed out the first clean can take double the time. Also the custy might desert you after first clean (doesn't happen often but there are still some unscrupulous custys out there).My thoughts are leaning towards offering an incentive to the recommending custy only if you are going to offer an incentive clean.Personally I dont clean any for free but can understand anyone who wants to build up their round wanting to do this.