My information is not taken from online material, but a text about the paintinig in Vincent Van Gogh (paintings) ,1990, Riksmuseum, Amsterdam, pp. 47-48
He completed the painting during April 1885. Early in April he made studies for the various figures; on "11th April or thereabouts" he made a rough drawing of the composition to his brother Theo, followed by a more accurate composition sketch" and reported on his progress with the canvas."By the end of April he "had succeeded in a relatively short space of timein executing the actual painting" In May "after the painting was finished" he was considering making a half-size copy of it.
