document everything you do.. I did rebranding for an electric company on about 1000 units. you dont know the repairs, when and how it was painted. The reflective stripes on some were inbedded into the paint and did not remove and was a real be-otch. and was also hard to get more $$ for those instances. i say play it safe, wait 30, same goes for inside mural on dry wall..play it safe, be smart, and have them sign off. ( Ive been burned b4)