I came across this today while searching for something else. It's a painting of a hand plane from the 14th century. That is the earliest depiction of a hand plane I have seen; I'm not sure how long hand planes have been in use but I'd guess much earlier than this. However it is always good to have evidence.
Admittedly, my knowledge of tools in history is pretty limited, as is my knowledge of the ancient Roman philosophy that influences the subject matter in this painting. This image, a detail of the fresco Allegories of Good and Bad Government painted by Ambrogio Lorenzetti in 1338-9, shows a woman holding a hand plane. If I find any earlier images I'll have to take note. For more details about this subject and lots of images of this and other frescoes, please see the marvelous book: Italian Frescoes, the age of Giotto, 1280-1400 by Joachim Poeschke ISBN-13: 978-0-7892-0863-7.