just say "ive been going a while" ,
Being honest,its tough out there right now , but not so tough theres no windows left. you will need every ounce of charm to get the work tho ,to get a toehold . no customer will put up with a shabby job either, so be sure you dont rush in the early days. if you have to do a window 5 times to be sure your happy with it-so be it .
besides, the longer you take ,the more other folk on the same street will see you in action.they might not see you the first visit,nor the second ,but in time they will .