I was reading Jamgon Kongtrul's Treasury of Knowledge - his encyclopedia of Buddhist knowledge as presented in Tibet in the middle of the 19th century - and in books 2,3 and 4, published as "Buddhism's Journey to Tibet" Kongtrul goes into the gradual development of Buddhist art.
It turns out that during the Buddha's lifetime there were at least two paintings made of him with his knowledge and blessing. One is a famous story of a painting make of Buddha Shakyamuni and depicting the 12 links of dependant origination. Another is a story of a painting made expressly to promote faith in a king and as an object of blessing.
Then the first statues of Buddha Shakyamuni also were made during Buddha's lifetime according to Kongtrul. The first was commissioned by a king during Buddha's visit to the Heaven of 33 in order to teach his mother. The king had invited many Arhats to dinner while Buddha was teaching his mother in the Heaven of 33 - they had left the head seat empty for the Buddha but felt the lack of his presence. The king commissioned the statue in order to compensate for the lack of the Buddha's physical presence. When Buddha returned to Earth he found out about the statue and then blessed it. Some other statue's were made that also carried the blessing power of the presence of the Buddha. This was in fact the aim of the creation of the statues.
This material is at the end of Book Four in the encyclopedia, so at the end of "Buddhism's Journey to Tibet" in a separate section discussing sacred Buddhist art.