hi
when i convered over 5 yrs ago i did a few at a time, as they take longer to begin with ,as you want to leave them feeling good about wfp, choose the ones that you think will accept it better , print a letter to outline whats involved, give to them before cleaning , when you convert more they will have seen you using it , the speed will come , but not before a lot of trial and error, there will be days when you consider going back to trad, but stick at it.
daz